TH350 clanking sound

Clanking sound on 56 chevy with th350 transmission. Noise heard when putting trans into Drive and while driving near 5mph not under load. Also similar noise when twisting output shaft.
I posted this video so I can send the link to a message board looking for a solution.

[@edshandymantips4862]

After several weeks the consensus on various hot rod forum I posted this video on seem to think it is either the anti clank spring (missing or broken) or broken or worn case tabs. The moving of the output shaft is a normal sound from the parking pawl.

[@RustyPumpkinRanch]

They do have a case saver which you can install and save the transmission if it’s worn. This problem exists in the th350, 700r4 and 4l80e. So it might be worth installing, I’m talking about the bolt in style which also makes trans much stronger. They make other styles, but they looks like they’d be ok for daily driver, but not a hot rod.

[@RustyPumpkinRanch]

Probably a bad case center support. When your moving it back and forth with the tail shaft removed, it’s in park, and your hitting against the parking pawl, that would be normal.

[@edshandymantips4862]

Thanks for your input! Had a chance today to get under the truck. The noise when twisting the output shaft happens when trans in neutral. No noise when in park. I think your correct and it may very well be the case and/of the case tabs. Going to put in a 700R4 so will be able to inspect the th350.