I talked with the buddy of mine whos truck it came off of he said he is fairly sure his tcase was the non heavy duty truck was a 99 model that it was on. Keep in mind guys that all gearvendors are the same unit only the adapters change for each application so no matter if you have heavy duty tcase, a 2wd, or even a 3rd gen this adapter can be sent in to gearvendor and get whatever adapter you need for your application.