Rotax 503 Muffler required

[microman]

I am currently restoring an old 95.10 Sapphire and need a muffler for the 503 engine which incorporates the 180 deg expansion chamber. I actually have two other mufflers - one with a 45 deg chamber and the other with a 90 deg chamber. I guess if all else fails I might be able to get a welder to modify one of these but would prefer the real thing. Problem is the old 503's are becoming a bit scarce! - any advice or help would be appreciated