Looking for advice with an Eaton RT-7608LL problem

First time poster here, lots of information here but I’ve searched for issues with the Eaton 8ll and haven’t found anything on this particular issue.

I’ve got a rt-7608ll in a tandem dumptruck with the 8.3 Cummins in it. We had an issue last year where the snap ring broke off in the trans and it was hanging up in 8th gear when trying to down shift…pulled the trans and took it to be fixed. Got it back and all has been great for I’d say 4000 miles or so until today.

hauling dirt on a short haul mid day,put the truck in fourth and heard a strange rattle/faint dull grind and it went away, get to drop site and go for reverse…no reverse. Try for reverse low and it engages but I hear that dull rattle/grind noise faintly. Engage high side reverse and same thing, works but the noise is there aswell.Check normal reverse gear again and nothing still. What gives? Drove the truck an hour back to the yard and everything was fine other than that little rattle/dull grind from a take off but then goes away. Im thinking maybe another snap ring failure but was wondering if anyone has any ideas other than that, im not terribly familiar with this transmission and their “nuances” so im stumped on what it could be any help would be appreciated thanks!