I am trying to figure out what rear seat was put in my 68 SS. I ordered seat covers from YearOne and the cover for the back was (56 inches)3 inches too long for both the top and bottom portions of the seat.The cover won't even fit between the two armrests. The rear seat which I believe is original is only 53 inches as is the space between the two arm rests (with ashtrays) therefore making the seat I have fit very snug on both top and bottom. If anyone could tell me what might be causing this dilemma me and my upholster would greatly appreciate it as I have to pay him for every day I don't find out.