I know when Calvert first came out with CalTracs years ago, he was recommending stiff multi-leaf springs with minimal arch and stiff shocks to keep the chassis separation to a minimum ("Wasted motion").
However, most of the pics I see these days of leaf-spring Stock Eliminator cars that are using CalTracs or Assassin Bars w/ similar ETs as my car show quite a bit of separation... almost as much as you'd see from the old SS springs or slapper bars setups.
