69 Sidepipe Part Numbers/Differences

[Jack O.]

I have a new set of original BB sidepipes numbers 3973871 and 3979480. Both have the W stamp on rear bracket but only the 3973871 pipe has the small tab with a small hole welded on at the rear of the muffler (picture below). I have an original set on my car as well and both left and right have this tab. Anyone know what it was used for? Was there perhaps a previous design that used this tab instead of the Z bar shown in the AIM. I see no production change note for the Z bar in the AIM though.
Thanks,
Jack

[Jack O.]

Re: 69 Sidepipe Part Numbers/Differences

Can anyone confirm whether this welded on tab was present on assembly line installed side pipes? Wouldn't think so if they're not used. Perhaps they just appear on some of the later produced OEM pipes. TIA