I'm looking at an '85 Seville, in excellent condition. I recall driving an uncle's '85 for a week end, back in the day. I remember it as wallowing around, as did Cadillacs of old. Since I would be looking to make a fair amount of use of this car are there any aftermarket suspension upgrades? Perhaps interchange from other GM cars? Riviera turbo? I am not looking to make it a BMW, just a significant improvement.