C-Clip vs. Cir-Clip!!!
The C-Clip is used to hold the axles in the differential, of a solid 8.8" axle car. It's sorta like a Lg. flat washer, with one side cut out. Hence the "C" name.
A Cir-Clip holds the axle stub in the differential of an 8.8" IRS car. It's like a split, spring steel O-Ring. It goes around the axle stub. When the stub is inserted into the side gear, the Cir-Clip expands into a groove cut in the side gear.
I have no idea why your friend thinks that the Cir-Clips need to be replaced, (maybe he has NO IDEA either!!!!!). Cir-Clips will not cause the problem you described.