why do $2000 replacing all the lifted parts (body mounts, springs, pitman arm (no fun there). (even wrong shocks now after the drop)
or drive for 5miles boots pulled off the top of 5 speed shifter shaft boots only removed. (when you buy jeep this old ,all things the OP did wrong, did not service you get to fix. (expect anything)
costing zero parts (yet)
costing labor 1/2hr, and a used $1 screwdriver.
learn what fails for sure first. if the boots are old and stiff after 30 years or the mounts are all a wreck. ( 30 years age things go bad)
if the engine/tranny motor mounts fail they move excessively and against old hard boots, and it jumps gear. (see both are bad and the effect is worse)
use a lever to test mounts, mounts can beat them self to death this is first. (or ask shop to do that)
why skip such an easy test (boots off). or ask others to guess what is wrong with your car, blind ,deaf and with no hands on driving. why?
why work the most expensive cure first?, are you floating in cash? guessing.
the fast cheap tests beat any kind of guessing, for sure.
also the rear prop shaft, if the pinon angle (done wrong) is excessive the rear of the trann/xfr case vibrates violently and can pop the gear, again take the boots off. the box. even drop the 4wd lever.
what is your rear pinion angle?. if not done right it will be a huge problem. is the transfer case
pan, have the 2 drop rails there? or not./?
many jeeps the mount on top of the pan just above, is a wreck, and is weak, and small./
The whole jeep needs a full check out first. fixing the most dangerous problems first.
is the screw driver lost?
with the boots off no kidding you can see if the tranny is jumping like mad, for sure 1 drives and 2nd watches safely