ORIGINAL: Baja5BLST

first try the roll test. Does it roll smoothly, without binding? If it doesn't, you got a problem somewhere.
Check the mesh between the clutch bell and the spur gears. See if they are meshed correctly. Do this by loosening the engine mount screws on the bottom, and putting a strip of paper between the clutch bell and the spur gear.(the ones closest to the engine) Now press, and tighten the screws. This sets the mesh. Now try the roll test. It might also be your clutch. Take the engine out, take off the clutch bell, and check the clutch shoes, and see if they are all right. It might be that they aren't right. Check by trying to pull out each shoe. It should be difficult, do to the resistance of the springs. If they won't move, no matter what you try(you might need a screwdriver to check), then this is your problem. Remove the shoes and springs, replace if necessary.
Also, check that it isn't your brakes that are binding. This might be the case.
It could be that you have lost the little set-screws that secure the outdrives to the tranny. Flip your truck over, and the outdrives attached to the tranny should have some setcrews securing the outdrives to the tranny. If not there, this is your problem. If they do, check that they are tight. Also, check that the CVD's are attached to the output shafts on the diffs(you must remove the two skidplates to check) with setscrews as well. if these are totally gone, or just loose, replace or tighten.
After checking this, report back with your findings. If this doesn't solve your problem, we've narrowed down the issues at least.