My Dads' 57 E Bird has a little sag to the rear and bouncey shocks in the front. For Fathers day and his birthday I plan to have the rear leaf springs, front coils, and shocks replaced. Any recommendations on which vendor to use? I also hear a vaccum leak in the power booster which, I think, is associated with the increase in engine rpm when braking. Is the vaccum booster diaphram difficult to change? Any vendor recommendations? I figure true TBird enthusiats know a lot more about these items than most general mechanics so your feedback is important. Thanks for your help.