Are the front and rear bumpers to a 71 Buick Centurion interchangeable with a 71 Chevy Caprice? My Centurion bumpers are just OK but I know of a very nice low mileage 71 Chevy Caprice with perfect bumpers that is available for a low price.
No external body parts were ever the same on this era GM cars from different divisions. Only oddball exception I can think of is trunklid from GS/Skylark shard with Chevelle and Monte in 70-72