I need a cheap PTO shaft cover.

[scootr]

Another vote for grease here. Cheap, readily available, and zero rust. But no harm in using a cover unless the shaft is not greased in which case it will rust.

 

[hslogger]

I keep mine lubed and capped. My implement end gets a dose of fluid film.

 

[gstrom99]

My Deere has a nice steel cap that clips in place. It's usually on. I don't use the PTO all that much, and since I DO grease it - it would collect all sorts of dust/dirt. I like the $9 one...