I have a Olds S88 with Hydramatic and 4p Rochester. The car was basicly equipped with a single exhaust system. However, in the shop manual there is a picture and a few lines that indiciates that these cars also had dual exhausts from the factory. The picture tells nothing about wich car where sold with what. My question is if there is any difference at the exhaust manifolds for dual system compared to single systems. /Daniel