1" shafts were used on all early inboard equipped Catalinas with the exception of the Catalina 250 (which used a sail drive) and the Catalina 42 (which used a 1-1/4" shaft). A 1/4" square key and a cotter pin are also included.

Just a note of interest... Although mild steel and hardened steel castle nuts are readily available, brass castle nuts are not. They must be individually machined for us from a heavy profile, commercial brass nut, hence the surprising cost for a single nut.