From what I have seen the early foam is better. The seats are interchangeable the backrest covers are not so you can't exchange apolstery. From 1989 on, the 240 seat foam is different. It looks almost white compared to the dirty yellow color of the older foam. All of the white foam in my 89 was ripped. I rebuilt the seats with foam from an 87. In spite of it being older it is much firmer and holding up well.