The 71-75 body mould was actually a stainless strip with flat insert, with retainers in body.
Firebird body moulds diagram 1972 by
Ben, on Flickr
Here's a few pics of NOS #488141, Firebird front fender.
NOS GM 71-75 488141 fender body mould black (3) by
Ben, on Flickr
NOS GM 71-75 488141 fender body mould black (6) by
Ben, on Flickr
NOS GM 488141 fender body mould black stainless 71-75 (1) by
Ben, on Flickr
NOS GM 488141 fender body mould black stainless 71-75 (2) by
Ben, on Flickr
The following are the same moulds used for B-bodies, different length but same details.
NOS GM 488142 stainless body moulds black B-body (3) by
Ben, on Flickr
NOS GM 488142 stainless body moulds black B-body (8) by
Ben, on Flickr
NOS GM 488142 stainless body moulds black B-body (9) by
Ben, on Flickr
NOS GM 488142 stainless body moulds black B-body (5) by
Ben, on Flickr