Are the aircooled RD 350.s exhausts same on US and European /rest of the world RD.s ?
fas as i know, yes, have seen the same #s referenced from the uk guys as we had.
r5 and rd are different #s but interchangeable.
360 & 521 code mufflers are different lengths
360 used on everything including USA 350 B are shorter than the 521's which were fitted to Uk & European 350B's.
Having said that it's pretty unlikely you'll come across any 521's over here.
Thanks