It would probably be simpler to have a local sheet metal shop fabricate a cover. There's nothing particularly important about its function except to protect the rotating parts from catching gravel or road debris and jamming it up into the bell housing. A reasonably competent tin bender could probably bang one out in a couple of hours. A piece of air conditioning duct work, a pair of tin snips, and a few pop rivets would be all I'd need to make a suitable cover.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!