I have a 48 chev sedan with stock rear springs and after market shocks and a Mus II up front. When you are cruising at freeway speeds (65 -75) and hit any bump or say a bridge she rocks back and forth bad enough that I have to let off the gas. Is it just overdriving the set up? I know others that have the same and really cruise. Maybe she needs sway bars, what do you all think?