I don't think there is a right answer, as every possible combination - probably happened.

I think there is a disconnect between what was "envisioned" as an engineer/designer/stylist's concept for the appearance of the 'Cuda/Challenger/Challenger R/T in conjunction with the SHAKER hood and what was done (or eliminated by the "bean counters" at the 19th hour) at the factory and/or dealer. In the "big picture" this look would include the bumpers/grill/hood/mirrors/tail panel as a whole. This was a minor detail for Chrysler Corp. with ~800 SHAKER cars out of ~1.5M produced for the '71 model year.



'71 'Cuda w/painted grill & Challenger R/T (black grill) = black SHAKER bubble
vs.
'71 'Cuda w/argent grill & Challenger (argent grill) = argent SHAKER bubble

* '70 was worse with body-colored bubbles & dare I say R/T SE finish panels.