I had the same issue with my 68 Charger front seats. I used legendary front seat foam and Legendary vinyl. I also had the re-use the original foam on my seat backs because the "new" foam wasn`t even close. I got so fustrated I actually had a friend who has done many sets of seats try it and he said the replacement foam was junk and used my original foam. I`ve done quite a few sets of seats myself and never had trouble like I did with these 68 seats. Try doing an early set of b-body seats...When I did those it was hard work but they came out great.