You shouldn't have ANY play. 1/2" is a major problem.

The play is either in your rear end or your transfer case. Remove the rear drive shaft. Now grab the input of the rear end and see if there is rotation. Do the same with the transfer case.

88 4R, 350 V8, R150 5 speed Sold <...uot; />
97 4R, stock, daily driver
98 Sienna, kid and dog hauler, wife's ride