In looking at the radio for sale on ebay, the 91BFP1, I think that radio would be correct for a full size GM car , such as an Impala, in 1969.
The web site www.wonderbarman.com breaks down the meaning of the alphanumeric code. It appears that the 91BFP1 would be out of a full size car and the Camaro would be a 91FFP1. The first F is for pony car such as Camaro and Firebird.
Any thoughts ? Am I mistaken on this?