Allowable backlash

You know what else happens with power, is that the cross-pin saddles egg out. If you don't catch it early and the cross-pin retainer lets go, then the crosspin can take off and try to exit thru the rear cover. It doesn't usually make it but when it jams up in there, nothing turns anymore. Yahoo! You're in for a ride
Well AJ you and Rusty called it.
Tore it down today and found that the shafts had worn into the case halfs, its junk.
Amazingly the ring and pinion look OK.
Question: Has anyone tried one of Doctor Diff's Sure Grip units?
For $395 it may be a deal, I also wonder about his $185 ring and pinion set?