what are the differences ? I wasn't aware they actually COULD BE different.

MegapartsUSA ( I guess by AMD advartising ) list them diff

( of course, this excludes 73 and lates Bs )

Can't speak for B, but 70-71 E passenger side inner fender has provisions to mount the horns. In 72 the horns moved behind the grille and the washer bottle moved to the inner fender.

between the 70 and 71 inner fenders the 70 has a rounded part by the shock tower on the r/s inner..I think most of the repros are copied after the 71 which is a sharp corner..cant tell you about the 72 and up ones..

70E only, some early 71, right does not have the knotch on the top that the 71-4 has.
72-4 left has a hump at the battery hold down that 70/1 does not have.
71 and 72 B body has the same as E-body for that year.

mmm interesting... I don't have totaly clear ALL the differences, but it looks they are really different, LOL. Maybe still interchangeable, but different

70/1 left apron

72-4 left apron

70 right apron does not have this knotch on the top. This is from a 71 with the vapor line in the knotch.