All 1994-1996 GM B-bodies (Chevy Caprice/Impala SS, Buick Roadmaster, or Cadillac Fleetwood) came with an option for an LT1 engine, the same engine used in Corvette for those same years. GM chose the LT1 because it adequately produced enough torque and horsepower to move the 4,000+-pound vehicles. The only real differnce between the b-body engines and the ones used in the Corvettes was that they exchanged some horsepower for torque (to get the big whales off the line a little better since they weigh more than the Vette) and the Corvette LT1 has aluminum heads.