today on my way home my rearend started knocking,for the first 20 sec thought it was a rod

,pulled off and the knock went away ,drove a little knockknockknockknock from the rear,so i limp home pull the cover and ring gear is beat up and missing teeth

this is a almost new ,installed it last year, new ring ,pinion ,bearings,etc.was checked by the guy who redid it for me And another guy i know before I installed it, both old timers,car guys who have done it a time or two, and lucas lube,so i think the install is not at question its a GM 7 1/2, 10 bolt 3;42, IS MY CAR TO MUCH for the 7 1/2?,quality issue?? i did just run it at the track also,so i think i may need to aquire a better rear end ?,My friend is loaning me his fresh 10 bolt with 373's with adjustable upper and lower controll arms temperaraly till i fix or replace mine as his body is still off the frame, Any one got one that will fit a G-BODY bigger than the 7 1/2 10bolt or a 12 bolt ,modified 9"?

,or a set of gears laying around for the 7 1/2 ,3;42-3;73