Hurt the 904 and 8.75 at the same time

You can put the stator support splines in the converter to engage it, then rotate it back & forth, try to make a complete revolution & see if it jumps/binds/hangs up in the free-wheel direction. Anything other than smooth & free is not OK. You can then check the turbine the same way with the input shaft, it should be free & smooth both directions,.....often if the sprag fails hard enough, it can spit damaged rollers out, they will be floating & getting knocked around in between the housing/impeller, turbine, & stator blades.
So I'm getting smooth rotation in both directions, no grinding or noises. I did both the input shaft and stator support, both are the same, no one-way action though! Is this the source of my noises?

Just an observation. The 5.0 kickdown lever is of no use without the Hemi width band......not available for the 904, but there some extra wide ones available. Without a wider band, that lever really does nothing and can actually slow the shift down. I've had it happen.
The wide one is rigid 2 1/16", narrow is not rigid 1 3/8", all frictions look close to new and are red. It wouldn't be hard to change the lever if helpful