727 Torqueflite Issues

Hello,
Looking for a little 727 Trans help.
Here is my set-up
1988 D100 Short Box
446 Stroker
GER Street/Strip 727 Torqueflite
I’m not even sure if GER is still even in business, the Trans was bought new in 1989 but I’d be surprised if it has 15,000 miles on it. It’s been in an 82 Mirada, a 36 Chevy Pick and a 1950 Ford Pick Up.
Here is the issue, when in reverse there is a clicking noise almost like the parking paw is not disengaging all the way. Went through the shifter linkage adjustment per the manual with no luck.
Put the truck up on jack stands and with the engine running shifted through the gears manually right at the transmission. Still had the clicking in reverse, and while in neutral wheels were spinning forward with power, I had to brake to stop them. Then as I put it back in park you can hear it slamming into park and you can see the wheels move until locked in.
Also some slight chattering noise while in park.

Any ideas??

Thanks
Author: Air Bubba