You don't have to. You can use ford or chevy stubs. The only difference is the chevy stubs are slightly longer and allow you to put the outer c-clip on. I've run both the ford and chevy stubs, and I don't use the c-clips on either.
sweet i was looking at it the other day and i was thinking the same (why did they put a c clip on the end)???? the shaft will only move a little so i wont worry.