Thinking about a new used truck

[4seasons]

I currently have a 1990 extended cab K2500 that handles all my hauling and towing needs. But I also have a wife and 3 kids that I take with me while hauling stuff on 2+ hour trips. My neighbor has a 90's C3500 crew cab sitting in a field with no motor or transmission. I am considering picking it up for cheap and dropping in a new engine/tranny and using it to pull my equipment trailer (12000 lbs) and still have a family plus load hauler for longer trips.
My question is regarding the engine and transmission setup that will give me the best fuel mileage and be reliable. I know that some Dodges with the 5.9 12v Cummins and NV 4500 have been getting better than 20 mpg highway so that is what I am shooting for. But I think that the straight 5.9 swap would end up costing more than the truck is worth, unless I find a steal on a wreck. I am wondering if the 4BT Cummins would be a better option and if it could get the same fuel mileage. I am not locked in on diesel though as I know maintenance cost on diesel is higher.
I know that the 350/turbo 400 combo in my K2500 doesn't come close to getting the 20mpg I would like to see. I also know that the 4.3 v6 only gets 20mpg in a S-10 so I doubt it can pull the Crew Cab dually with much fuel mileage. I know that both LT1 and LS1 can get over 20 mpg in a Camaro but I don't think they would do it in a truck that weighs twice as much. I am not locked in to Chevy engines especially if there is something that will achieve my goals.
Am I insane to think I can get 20mpg empty out of a Crew Cab Dually? Does anyone have one that does? 20 is just a nice round number, so if it can only get 18-19 that is fine, I just want to get some brainstorming before I spend money, or dust off the engine hoist.

 

[Ryan'smilling]

I currently have a 1990 extended cab K2500 that handles all my hauling and towing needs. But I also have a wife and 3 kids that I take with me while hauling stuff on 2+ hour trips. My neighbor has a 90's C3500 crew cab sitting in a field with no motor or transmission. I am considering picking it up for cheap and dropping in a new engine/tranny and using it to pull my equipment trailer (12000 lbs) and still have a family plus load hauler for longer trips.
My question is regarding the engine and transmission setup that will give me the best fuel mileage and be reliable. I know that some Dodges with the 5.9 12v Cummins and NV 4500 have been getting better than 20 mpg highway so that is what I am shooting for. But I think that the straight 5.9 swap would end up costing more than the truck is worth, unless I find a steal on a wreck. I am wondering if the 4BT Cummins would be a better option and if it could get the same fuel mileage. I am not locked in on diesel though as I know maintenance cost on diesel is higher.
I know that the 350/turbo 400 combo in my K2500 doesn't come close to getting the 20mpg I would like to see. I also know that the 4.3 v6 only gets 20mpg in a S-10 so I doubt it can pull the Crew Cab dually with much fuel mileage. I know that both LT1 and LS1 can get over 20 mpg in a Camaro but I don't think they would do it in a truck that weighs twice as much. I am not locked in to Chevy engines especially if there is something that will achieve my goals.
Am I insane to think I can get 20mpg empty out of a Crew Cab Dually? Does anyone have one that does? 20 is just a nice round number, so if it can only get 18-19 that is fine, I just want to get some brainstorming before I spend money, or dust off the engine hoist.

I think the only possibility that will get you close is the 5.9, but honestly I don't think actually see much better than 15 in a dually.

More importantly, in my personal opinion, you'd be better off just buying a dually with a 454. They're not very expensive. If that one's been sitting in a field very long it's gonna need tires. Six of them. Another point to consider is that fuel economy is great, but you have to think about overall operating cost. I paid $4000 for my k3500 this summer. It's got 4 new Michelins on the rear and two not new but good Firestones up front. Best I've gotten is 11.3mpg worst is probably 7 towing 12,000# in town. BUT gas is a lot cheaper than diesel right now. An oil change is $40 for me. It's a fair amount more on a diesel. Yeah, it isn't exactly fun going to the gas station, but I still consider that truck cheap to operate if you look at what it does and how much I have into it.

 

[Natster]

Sign up for TDR.COM That's Turbo Diesel Register. It's a forum for cummins enthusiasts. There are sections there for engine swaps, Fummins, (Ford bodies, Cummins engines) and all sorts of things. The Cummins motor is a straight 6, and it's pretty long.
There's a minor fee, (at least there used to be) for this forum. But, the information is top notch.

 

[stihl sawing]

Sign up for TDR.COM That's Turbo Diesel Register. It's a forum for cummins enthusiasts. There are sections there for engine swaps, Fummins, (Ford bodies, Cummins engines) and all sorts of things. The Cummins motor is a straight 6, and it's pretty long.
There's a minor fee, (at least there used to be) for this forum. But, the information is top notch.

No fee to use the forum , the fee is for the magazine and some other stuff.

 

[stihl sawing]

My 24 valve 5.9 gets close to 20 not pulling. my 6.7 not so much.

 

[FlyingDutchman]

A 6.5 turbo diesel truck might get close to 20 with a few mods, tall gears (3.73 and numerically lower, and if you are lucky. My K1500 truck with 3.73 gets about 16 average winter/summer which is not bad. I beat the hell out of it and its tuned and it doesn't roll unless I'm doing something worky. I need injectors which may help mileage quite a bit. It's been a long tough road just keeping it on the road but also doing so while improving the performance. Boy, I have a tough time recommending one to anyone. Some of these trucks are just a nightmare. Takes patience, research and dedication to keep it reliable. I also say, if you are lucky. Some people just have crap mpg.

A 5.9 12v is a very good swap into these trucks with the nv4500. It improves the value of the truck quite a bit, if you have a P-pump especially and tackle issues like the KDP (killer dowel pin), and freshen up common leak points. The performance potential is way way better than a 6.5. 6.5 you start to have problems with the block cracking even at stock power levels. Most people barely touch 300 hp with all the bolt ons you can shake a stick at Cummins with a modified P-pump throttle plate, and the boost turned up beat that easily. But, you have to swap the truck and go through that hassle. Not a simple or quick task.

However, the 6.5 is a smoother, quieter engine. My engine is straight piped and pretty liveable stock. Cummins drone awful. I personally hate the sound of them. 6.5 is also lighter than a 5.9 by a couple hundred pounds.

You can buy a shitbus of gas for whatever you stick in a diesel. I don't know if I'd buy another after the hassle I've been through.

 

[4seasons]

A 6.5 turbo diesel truck might get close to 20 with a few mods, tall gears (3.73 and numerically lower, and if you are lucky. My K1500 truck with 3.73 gets about 16 average winter/summer which is not bad. I have a tough time recommending one to anyone. Some of these trucks are just a nightmare. Takes patience, research and dedication to keep it reliable. I also say, if you are lucky. Some people just have crap mpg.

A 5.9 12v is a very good swap into these trucks with the nv4500. It improves the value of the truck quite a bit, if you have a P-pump especially and tackle issues like the KDP (killer dowel pin), and freshen up common leak points. The performance potential is way way better than a 6.5. 6.5 you start to have problems with the block cracking even at stock power levels. Most people barely touch 300 hp with all the bolt ons you can shake a stick at Cummins with a modified P-pump throttle plate, and the boost turned up beat that easily. But, you have to swap the truck and go through that hassle. Not a simple or quick task.

You can buy a shitbus of gas for whatever you stick in a diesel. I don't know if I'd buy another after the hassle I've been through.

I have never heard anything good about the 6.5 Detroit in the Chevy. I assume that this is the engine you are talking about.

I have thought about the gas options also, but I know the 454 is a thirsty beast although there is no lack of power or parts. I am quite familiar with the SBC as I have owned a 283, 305, 307, and 350. Although I am not concerned with total HP and Torque numbers as I only need it to pull heavy from time to time. I also have a 292 inline 6 that needs some work in an older Chevy, but I don't think it will perform in a crew can dually very well. Not sure if any came equipped that way to compare. I have also thought about the 500 Caddy as they are torque monsters. But I have know idea how much gas they use.

 

[ChoppyChoppy]

I've run a few dozen 5.9L Cummins, 1st-3rd gen, never have seen regularly over 20 mpg out of any.
They are a great engine, but there are certainly plenty of "fish size" exaggerating that goes on!
I remember filling up and people coming by, "must be nice to have that diesel and be getting 35mpg".

Most have averaged about 15mpg. The best was a 93 that averaged 19-20mpg.

The best tank I ever got in my 98 was 18 mpg. I drove that truck about 125,000 miles. Towing it averaged 12-13mpg.

 

[FlyingDutchman]

Yes I'm talking about the Detroit. It can do exactly what you are looking for- fuel economy wise, with low expectations power wise unless modded. 300hp is still like 550lb ft torque. Don't discount it as an option, but it's not an easy path.

The early 90s 12 valves with the rotary pumps were nowhere near the powerhouses the PPump trucks were. They were efficient because they were detuned.

Here's a vid of my truck accelerating.



My grandfather had a quad cab dually Chevy with a 472 Cadillac engine, the s It probably had close to 400 horse out of the box. It got 10mpg if it was idling on a flatbed trailer being towed. Plenty fun though. Boy would she howl when the secondaries opened up on the 4 barrel!

 

[4seasons]

My grandfather had a quad cab dually Chevy with a 472 Cadillac engine, the s It probably had close to 400 horse out of the box. It got 10mpg if it was idling on a flatbed trailer being towed. Plenty fun though. Boy would she howl when the secondaries opened up on the 4 barrel!

That is kinda what I thought I might expect from a big Caddy. But I have no experience with one so I thought I might be surprised.


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[4seasons]

I've run a few dozen 5.9L Cummins, 1st-3rd gen, never have seen regularly over 20 mpg out of any. The best was a 93 that averaged 19-20mpg.

The best tank I ever got in my 98 was 18 mpg. I drove that truck about 125,000 miles. Towing it averaged 12-13mpg.

These are the 20 mpg ones I was thinking about. I have driven a standard cab dually on its third auto trans in a company truck with the 5.9. I don't remember what year it was but I do remember trying to beat a delivery deadline with just a few boxes in the back up US19 through Virginia. On one of the longer pulls up through there I actually was racing a Miata that I ran off on. I wasn't pushing it near as hard on the way back but I still averaged 18mpg on a 400 mile trip. I am almost certain that if I babied down the interstate it could have gotten better than 20 even in an automatic.

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[rwoods]

Probably more than you want to spend but probably less than the total cost of a diesel conversion. https://tricities.craigslist.org/cto/d/lebanon-03-duramax/6798189467.html

https://tricities.craigslist.org/cto/d/church-hill-2002-chevy-dually-4x4-1-ton/6764024240.html

Ron

 

[Ryan'smilling]

Probably more than you want to spend but probably less than the total cost of a diesel conversion. https://tricities.craigslist.org/cto/d/lebanon-03-duramax/6798189467.html

https://tricities.craigslist.org/cto/d/church-hill-2002-chevy-dually-4x4-1-ton/6764024240.html

Ron

That's 13K for a 17 year old truck with 300k miles on the clock. Seems nuts to me.

 

[4seasons]

Probably more than you want to spend but probably less than the total cost of a diesel conversion. https://tricities.craigslist.org/cto/d/lebanon-03-duramax/6798189467.html

https://tricities.craigslist.org/cto/d/church-hill-2002-chevy-dually-4x4-1-ton/6764024240.html

Ron

Yeah, you are right about that being way more than I would spend. You have seen my current truck. It falls into the not much to look at but runs great category. I am more of a junkyard dog type that will by two junk trucks with good parts and put them together to create a one of a kind mutt.

 

[rwoods]

That's 13K for a 17 year old truck with 300k miles on the clock. Seems nuts to me.

Don’t disagree, but used trucks around here aren’t cheap. You should try to find an affordable straight axle Tacoma. Prices are ridiculously high.

Same for 4wd compact tractors with loaders. A 17 year old can be 2/3 the cost of new.

Ron

 

[rwoods]

Yeah, you are right about that being way more than I would spend. You have seen my current truck. It falls into the not much to look at but runs great category. I am more of a junkyard dog type that will by two junk trucks with good parts and put them together to create a one of a kind mutt.

My kind of guy.

35 years ago, I put a junk yard Olds diesel in a Landcruiser. Now that is nuts, but I did. Spent a lot of time and $$$ making exhaust manifolds, steering relocation, bellhousing adapter, twin flywheel adapter, linkage, etc. only to have the engine lock up - or so I thought. Went conventional and bought off the shelf parts to replace with a junk yard SBC. Still spent $500 at a local shop to get it finished. Back to the Olds diesel, upon disassembly I discovered that the engine wasn’t locked up after all, the flywheel was hung on the starter. So close to a 25 mpg Cruiser. But probably for the best as the injector pumps on those engines were trouble prone. And the engines were pretty weak power wise.

I would still love to have a diesel Landcruiser - maybe a bread truck Cummins 4 cylinder.

Ron

 

[mdavlee]

Don’t disagree, but used trucks around here aren’t cheap. You should try to find an affordable straight axle Tacoma. Prices are ridiculously high.

Same for 4wd compact tractors with loaders. A 17 year old can be 2/3 the cost of new.

Ron

Used diesel trucks are getting more expensive since the cost of a new base model is pushing $50k plus the complex emissions systems are causing reliability issues. If I never left 100 miles from more than once or twice a year I’d be driving early to mid 2000 models instead of a 17 with warranty

 

[rwoods]

Still traveling the country, Mike? Hope all is well.

Do you know any cheap trucks around here that might fit the bill for our friend?

Ron

 

[mdavlee]

Still traveling the country, Mike? Hope all is well.

Do you know any cheap trucks around here that might fit the bill for our friend?

Ron

I am. Actually out of the country at the moment.

I can’t think of anything right off. If they expand their search to Arkansas/Oklahoma there’s a lot more cheaper trucks that’s been used as farm trucks.

 

[Ryan'smilling]

Don’t disagree, but used trucks around here aren’t cheap. You should try to find an affordable straight axle Tacoma. Prices are ridiculously high.

Same for 4wd compact tractors with loaders. A 17 year old can be 2/3 the cost of new.

Ron

I hear you. Tacomas are silly expensive. My wife bought a 97 2.7l, 5 speed, manual everything. Paid $5900 in Washington. This was probably 2010 or so. Drove it hard for a year doing restoration work in northern California. Lots of Jeep trails to get to work. Mostly pulling Scotch broom. Anyway, sold it when we left California for $7500. Only had it listed for a couple of days.

Same with tractors. When we moved back to the farm in 2013 we bought a 47 hp Kubota. I looked hard for a used one, and as you said, good luck finding a real bargain. So we bought a new one.