I posted these pictures in the "Wood Hauler" thread:
I've got a modified 22RTE turbo engine under the hood and 3.90 gears (stock were 4.10) for a little better mileage. The rear springs consist of a stock replacement main leaf and leaves pulled from the spring pack of a 91 2WD 1/2 ton Chevy then shortened to fit the Toyota main leaf. I put plastic spring slides between the leaves and the truck rides far better than it ever did stock. I was worried about the axle but after looking up every part in an 89 1 ton single wheel rear axle and comparing them to the parts in my 4wd axle, no worries there. Toyota builds the 4wd axle the same as the 1 ton. But if there are problems I'll find a Ford 9" with 3.90 gears to install. The truck will consistently haul more wood than the brakes should be trying to stop so I may have to do something there. You can read more about the truck here:
1991 Toyota Pickup
Overall your truck doesn't look like a typical rusty Toyota from this area. Check the frame where the front hangers for the rear springs are attached. That's a common place to find rust, esp. on the passenger side. The section of the frame around the round brace over the rear axle is typical, but be sure and check the round brace for rust. The countershaft bearings in the trans will fail with high mileage and it's exaggerated with heavy loads. You can hear it as whining in every gear except 4th. I've got 200k+ on my truck and the trans is on the way out. It makes more noise on the highway than the tires and I have to hold it in 1st gear when taking off. I have a replacement trans waiting to go in after wood gathering is over. You want to haul a trailer but I'm not sure the trailer should carry much weight. The truck is light enough in the rear that a heavy trailer could push it around pretty good. But maybe a small trailer for tools would work. I still don't feel my truck is ready to haul my tandem axle car trailer but maybe I'm just being too cautious.
I'm a GM guy from way back but I've owned 3 Yotas and none of them have let me down. I'm sure yours will work hard if you ask it to haul wood.