The transmissions in our over the road trucks were very difficult when someone mistakenly put hypoid in them instead of straight mineral oil. Now we use 50 w synthetic. Also, the the overdrive in every vehicle other than GM uses a Warner front section. Chev mated their own front box to a Warner overdrive tailshaft. The Warner boxes used brass synchros which were attacked by the hypoid gear oil. Have fun removing it. They weigh over 100 lbs.
