TO-30 PTO Shaft and Replacement

What PTO shaft fit in a TO-30, and will an aftermarket 1 3/8 shaft fit in it?

The TO-30 came with a 1 1/8″ PTO shaft originally. As for the 1 3/8″ replacement shaft being longer, check the length of the shaft from the back of the bearing support to the end of the long end of the PTO shaft. It should be the same length as the 1 1/8″ shaft. The extra length should be on the 1 3/8″ splined end of the shaft which means it also requires a longer PTO cap.