One other thing to check is the drive shaft length. And not just at rest. Usually, if the drive shaft/rear end/suspension is just "bottoming out" for a split second and then freeing up, it will just get the thrust bearing. If the drive train is bottoming out and staying that way, it will burn up the rear crank thrust surface.
Good call. I have actually corrected this on this car. When I got it the driveshaft was way tight to get in and out
If it's a torqueflite, and just about every other transmission out there, forward axial thrust on the mainshaft (output shaft) will not transfer that force into the torque converter. A forward thrust on the mainshaft from the driveshaft will push against the rear annulus gear to the rear planetary to the sun shell to the front drum and into the pump cover (aka stator support) which is bolted to the pump housing which is bolted to the transmission case. UNLESS you have some serious damage in the transmission.
Issues of ballooning or forward thrust of the converter usually involve too much hydraulic pressure in the converter, restriction in the cooler or cooler lines, or sticking converter control valve. Converter pressure = 30 psi. Cooler line after the control valve = 10-30 psi in drive.
Converter control valve dumps into the pan at 60psi.
You may want to tee-in a pressure transducer or manual gauge in the cooler output line between the transmission and the cooler.
