I've searched for threads and haven't found a definitive answer on decent fitting seat foam. I did contact Wellington as one thread suggested and got a reply referring me to OPGI as Wellington does not have a direct replacement. On the OPGI site, I found this replacement foam: https://www.opgi.com/riviera/1972/interior-accessories/seat-accessories/SF00024/ In looking at other applications, I can't help but to think this is a one size fits all. The bucket seats I have are really beat up and my Riviera will be getting an interior overhaul in the future. I'd even consider installing a more popular cover with correct foam for that cover and replacement backs as necessary ('70 GS?) if the seat frames are the same. I know the tracks aren't. That way I can sell the seats in the future once changing out the interior. This will not be a factory correct car as I have it planned. Advice and/or experience welcome! Thanks.
I think 75 76 park avenue bucket seats are the same except they added more stuffing like they have in pillows to the seat bottom. 1970 would be narrower if I recall
http://www.chevelles.com/forums/26-...et-seat-guide-identification-1966-1972-a.html Great resource...
Seat frames are all the same across marques. The foams differ depending on the style of cover. I bought chevelle foams for my 69 figuring my upholsterer could "make them work, but he said that the attaching panels are unique for my Riv and the chevelle foams won't work. he reused my old foams and padded them up. If you aren't going with the last gen Riv seats, just go with a basic cover and foam. Just pick a style of cover you like. With a similar cover the difference between front and rear seats will be negligible.