My truck has a Raven camper shell (no longer in production) with two locking T-handles. The original T-handle shafts were threaded, with hefty cam locks held in place with lock nuts. The locks and T-handles being worn I decided to replace them. I could find no replacements with threaded shafts -- all shafts are square and plain. Replacement cam locks looked flimsy and are fastened to the square shafts with one puny screw threaded in the sheet metal of the cam lock.

So maybe an automotive machine shop could thread the shafts. No!

Pictured is my solution: a double split shaft collar, clamped to the square shaft by allen bolts. The rejected cam lock is to the right of the new T-handle.