Does anyone know the difference, if any, between the mufflers for the xs500e, which are given part nos. 371-14711-06-00 and 371-14721-06-00, as best I can tell, and the mufflers for other years (1975-1977), which have the same part nos., but end with an -04 or -05 instead of -06?

Also how can you tell them apart visually? They all appear to be stamped with only the first two portions of the part number (i.e. "371-14711"), without the suffix -04, -05, or -06.

And what is the downside of using an -04 or -05 suffix muffler on the 1978 xs500e?

Thanks.