The truck is not abused in any way, I try to baby it. When I first changed the adapter I pulled a stock trailer 200 mi with no problem, no leakage. Other than that it has been light ranch usage in 4WD and short hops to town. I wonder about the torsion involved in 4WD although the ground was wet.
I don't know the model of the T-case but it is the stock one that came with the '86, aluminum case, takes ATF and doesn't leak a drop. The old T 19 is kind of growley but seems fine when it is full of 90w, this is what leaks out of the adapter.
When I changed the adapter I found the front universal on the rear driveshaft had failed. When I went to put in a new one it would not fit, I had to do some grinding with a dremel to get the cups in. The bores were kind of egg shaped. The new universal failed and I have changed the yoke, that is when I discovered the adapter cracked again. The rear mount is under the adapter and is nice and tight. I need to get under there with a bar and check the motor mounts but I see no rocking of the engine.
Thanks for all the help guys. These forums are great. Most of the problems that occur with these trucks have happened to someone before. When I read of all the problems that others have had I feel lucky that I have had so little trouble with mine. Hopefully I can get this fixed right.
Tom