Please elaborate on it being an "auto" tail housing. There is not any intercahangable. I'm probably not getting it, lol. At least you ate making progress!! Thanks for the updates.
So from what I know there is a Auto vs Truck OD variation.
The cast iron truck OD I had a couple of years ago used the larger front driveshaft yoke.
I have a passenger auto OD here that uses the smaller front driveshaft yoke.
I hope that is a little clearer.