I recently bought a Camaro ex drag car and it also had a 10 bolt with a Richmond mini spool in it. The rear end had a lot of slop in it too, you could turn the input yoke a good amount either way before it stopped. I kept the parts I wanted off the car and scrapped it with the rear in it..........it just didn't seem right to me and not something I wanted. The play on mine seemed to be where the axle splines entered the spool.

Not sure if that is a by design thing, but it sure seemed sloppy.

Don