I am having a hell of a time. I am working on a 70 with an r151 trans. The trans is worn and the tcase has a hole in it. Rather than rebuilding everything I sourced a new unit from an hzj79 mine truck thinking all r151s are the same. Wrong. The new 79 trans is 1.5" longer in the 5th gear housing for some reason. And the mounting brackets are different. Now my rear driveshaft is too long. And front too short. When did these changes take place???