I have a 582 and the exhaust mountings keep breaking!!!!!
I have tried the types you get at Midas and they are the biggest rubbish ever!!!!
Last rubber lasted all of 2 minutes before tearing in half.
The mounting rubber is round ( the size of an old 20C piece with a threaded pin on each side, 1.25 pitch thread.
The original rubber bushes lasted for ages ( good quality ) 110 hours

Can anybody help with supplier who has good quality ?????????
the exhaust hangs underneath the motor & if these rubbers break off you stand to mince the prop
& exhaust canister. I have a safety cable attached but NOT good enough.