If your interior looks stock then it is most likely in the stock place. usually it is pretty obvious from the interior work (shift boots, carpet etc) when the transmission has been moved from it's original location
What’s wrong with your 84 case?
If transmission is in the original location you will just need driveshafts modded and later t-case linkage.
Highly recommend 10% OD Tcase gears in addition as well. Especially with the V8