The device shown in the Thumbnail appeared in the down pipes of M110 engines in the USA 1973-74, and the rest of the world until catalytic convertors were mandated. It was not used with any of the earlier six cylinder engines to my knowledge. It could conceivably function for tuning purposes, or for sound purposes. It does not appear in the FSMs, presumably because there was nothing to service.

Comments solicited:
a) Speculation
b) Trolling
c) Actual engineering knowledge from MB

Attached Thumbnails