Anyone have the GM part # for 1976 Grand Prix rear bumper?

Trying to find out the GM part # for my Dad's '76 Grand Prix's rear bumper. It's rusted all to Hell. Found a couple recently on Ebay listed for other
years ('74 and '75). They *look* like they are the same from '74 through '77, but I need to be sure that there are no differences. Anyone know? Car has been in our family since new. We want to do a complete resto on it with as many new original parts as possible. Hardest piece to find is the original GM weatherstrip for the power sunroof. Aftermarket doesn't make it. Universals don't fit. :o(
Helmut Roner 1988 Mustang GT
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