There weren't front fender extensions, they are '70 Coronet fenders with the lowers trimmed off and slightly built up on the peak where they match up to the nose.
I think the OP meant the lower front fender to valance extension corner pieces, basically an extension of the front fender to the lower valance center panel
I offer those in fiberglass if interested? molded off originals, all flanges are present, rear window plug (Superbird) in fiberglass as well if interested?
Mike