Do I have a sure-grip or not?

Back in the mid 80’s I ran a Chevy circle track car with a stock 10” rear and we never broke a C-clip but we did break a right side axle once.
Where was that at? I raced dirt track in Pa and Ohio in the early 90's and Chevy differential were banded because they broke so many of them. I saw one come off while on the track and it went through the pits. Axle, brake drum, tire and all. Lucky no one got hurt but it did go into a trailer and boy was it ugly! That put an end to any Chevy differential at Wayne county speedway.