So...
The transmission guru told me he thought my drive shaft was the cause of my trans failure. I believe he knows WAY more than I do, so I'm inclined to believe there's something there.
It seems absolutely fine with my old trans. No vibrations, all smooth, no issues at all except the trans isn't tough enough for the power being old and stock lol.
No idea what would be different between the two. Except.....
The tail shaft.

My 95 has this full spline one for sure.....
But my 2005 one had threads in the end like a fixed yoke would have, and I'm fairly positive it did NOT have splines all the way down.
So, could have caused a wobble at full stuff. Which leads me to my other observation.
I think my shaft is too long!


No seriously.... When the truck is under its own weight theres about 3.5" between tire and fender lip. But when it's on the lift it's more like 15"-18".
At that full drop spot, when I take all my u joint bolts out and push it forward to remove it, it moves about 1/2" past the diff yoke and stops.
Now that I lowered it, I wonder if I'm shoving the Dshaft up the trannys tail just a little to far

I've killed 2 tail new seals on the back of it, one in the old trans, and the one from the "rebuilt" 05 was leaking when I took it apart too.
There's a race shop near me. I'm thinking about asking them who they recommend for a new aluminum shaft. Then dropping the truck off with them and having a new one built to it.
First thing I'm going to do when I get the trans back in, is lower it so all the weight is on the rear axle and see how much play the Dshaft has back and forth.
And probably also should figure out some limiter straps for the tail
