I may stand corrected here, but I think the 69 model was the only C3 fitted with factory sidepipes. Having said that tho, I put a set on my 77 and to date have had no problem with legality......meaning I haven't been pulled over by the lads in blue because of them.........yet!
My 64 has them as well and I don't think that model C2 had them either, but that one isn't on the road yet.
I imported the "headers" for the 77, but had the sidepipes made up.
I will be making new baffles for the 64's pipes so if you want a set of sidepipe mufflers in good condition you are welcome to them if you remove them yourself.