This GM Performance Parts Hydraulic roller tappet camshaft is used in the ZZ4 - 350 crate engines.  Mild camshaft with slightly rough idle, can be used in all 1986-99 305-350 engines originally equipped with a hydraulic roller camshaft. It can also easily be used in non-roller 1986-99 305-350 engines when used with lifter kit 12371042. Makes excellent power and torque at low RPM"s. Great choice for street/strip and daily driven cars or light trucks.