That would make sense. The E body 4 speed, and B body with buckets and 4 speed used the same floor and rearward mounted shifter hump. The B body with bench seat 4 speed used the forward mounted hump, similar to the 66-70 floor, so they may have carried the earlier carpet and heel pad on. I question how well the 66-70 type carpet would fit though, since the floors were a bit different in shape. Probably not enough to be a problem though.

However, in all my automatic transmission 71-72 B bodies, they have all had the E body type heel pad with the corner notch.