TH350 Low-Roller Help?

[SkinnyG]

I'm chasing a coast-throttle rumble/vibration I can physically hear from the back of the transmission case. I can feel it through the pedals as well. Accel it goes away, decel it goes away. I can make it do it in 3 and 2, but not 1 (though I may not be going fast enough in 1 - it -seems- to be road-speed related).

Trans was completely rebuilt two years ago.

Over Christmas I pulled it apart, and replaced the extension bushing (which looked perfectly fine), the rear case bushing (which looked perfectly fine), and the front pump bushing (which looked perfectly fine). I also changed from the narrow direct drum bushing (which looked perfectly fine) to a wide bushing. All other bushings look good. Rear torrington felt "crunchy", so I replaced it with another, and shimmed end play within spec.

No improvement.

Today I pulled the low-reverse clutch, because that sort of made sense to me. Does anything here look out of place? It looks perfectly fine to me. I cannot feel even an inkling of wear or anything, it is super smooth.

Any thoughts? (click the image to biggie-size it)