yes there is.it's about a $200 difference only kidding,as far i know,they are the same.the part that bolts to the exhaust manifold is the same but the adjustment bracket i think is different. the exhaust manifolds are different as they have a larger diameter exit.
According to C2O.. there is a difference,!! 16 bucks for the regular one & 36 bucks for the L79. All cast exhaust manifolds were the same, whether it was a 283 or a 327!! If someone is selling an L79 set & say they're a larger dia.??