does anybody know if it is possible to make a 1986 toyota pickup with a flatbed (gardener style) into a 4wd solid axle truck with a flat bed? and if so how hard would that be?

 

be allmost the same as an IFS swap, just you have to find a tranny and xfer case to put behind ur motor, and ur gonna need the front AND rear end.....the 2wd rear is a 7.5 and the 4wd is a 8" also the 2wd's have a lower gear ratio...so ude just be better off buying the 4wd axle's in a pair that way you allready have the right gearing...so some welding fabrication...and a crossover steering kit..399 at wabfab, addictedoffroad, or trailgear...they also sell the IFS eliminator kit for 1500 ish with a front end rebuild kit.....

 

Anything is possible if you throw enough time/money at it.
My brother started with a 2wd for his 1uz/1tons build.

 

totally possible...
... BUT ...
the 2wd and 4wd chassis are somewhat different.

You already mentioned SAS, and that would be the way to go, even though there will be a lot of fabricating.

The 2wd trucks put the rear axle on top of the leaf springs so that needs changed with new perches mounted on the top of the rear axle housing and appropriate modifications with that, which will probably include lengthening the drive shaft.

Stop, think, plan. Draw pictures on paper, befores and afters.