The Velvet Drive "71C" and "72C" designations indicate input horsepower ranges. There are two basic configurations of transmissions in the 71 and 72 ratings are "Direct Drive" and "Reduction." Both versions are "In-Line" meaning the input and output are concentric. The 71C is only available in a Direct Drive version, while the 72C is available in both Direct Drive and Reduction versions.
Both the 71C and 72C offer reversible pumps to allow the use on a counter rotating motor (non automotive rotation).
Note: Reversing the pump does not reverse the rotation of the transmission, rotation is still dictated by the engine rotation.
Direct Drive versions of the in-line models are frequently used on high horsepower, light weight boats. The Reduction ratio versions use an additional planetary gear set to allow the use of larger propellers at slower speeds.