The Garrett (tree Farmer) is anvil simple. Parts are all at NAPA. Full time 4wd, they crab walk fierce, and a sidehill will give you high blood pressure it will crab so bad. If it has a 353 Detroit (and it prolly does) buy stock in a hearing aid company, and buy a case of ether....and a 5 gallon pail of oil every week.
The 440 Deere is a little more complex, but it's faster, better on fuel, has lock in lock out axles (That alone is worth buying it for) and will usually start...and usually doesn't eat oil.
The only real downside to the 440 will be buying parts from Deere or aftermarket..likely a bit more expensive.
I'd buy the Deere. And I have owned a Tree Farmer...quite a bit newer than the Garrett aged stuff...but basically the same thing.