I think I see a groove on the transmission (facing inside) end of the shaft (and a keyway?), but not on the outside end. There is a darker discolored ring on the shaft just to the outside of the outside end bearing but that does not look like a groove.
I don't see how having a clip in the groove on the inside end of the shaft is going to keep this from happening again. It keeps the shaft from being pulled out of the bearing.
It'd also need a circlip inside the transmission case, the size of the outer bearing race (plus groove depth) to keep the bearing from being pushed in. 2.75" sounds like that might be it though.