In an E body?

ALL THE TIME

I've seen 3 speaker with an AM
I've seen 1 speaker with an AM/FM
I've seen AC pad in a non H51 car
I've seen 70 pad in a 71
I've seen 71 pad in a 70
I've seen a black 71 pad in a burnt orange interior car
I've seen Barracuda pads in Challengers and the other way around.
I've seen a /6 pad in a 440 SIXPACK car

Face it. These pads failed early and often and were changed out with the next best pad that fit.

I have NEVER seen a car with a factory incorrect installed pad. Think about it! The dash assembly is done all at once. If you use the wrong pad the parts won't work out. Much harder to mess up than a torque box.