I wrecked my exhaust pipe rain "flapper" while clearing brush. I asked Mrs. seiscat for a can to use as a rain cap. She provided the cap shown below. It is a porcelain spatter-ware canister. It is rust proof, it will not hold water(when used as a rain cap) and is heavy enough that even the wind from the tractor being transported will not displace it.
She purchases these items at garage sales and such to make floral displays etc. These canisters are inexpensive when they are part of a broken set and can be found in various sizes.

Well it is cute! And functional.

That looks good, do they come in yellow?

Nice! With the porcelain finish it should last almost forever, just look at how the old porcelain signs resist the elements.

lol! Ha! That's what I have on my 7E! its more of a cooking pot though, mines blue, I just removed the handle. Gary

How much does it hurt when it lands on your head when you forget to take it off in the excitement of starting your Cat?

I use old Basketballs for rain caps. Cut a hole in the ball just a bit bigger than your exhaust stack and slip the ball over. It won't rust. It doesn't put a dent in your hood if you start the engine and forget to pull it off the stack. Works great!!

Only problem, when I go to put the ball on my exhaust stack, the dog thinks it's play time.

An old boot works in a pinch

I hope this helps...
Craig