This is the Tremec T-56 six speed transmission.

The T-56 six speed manual transmission has been used in a wide range of vehicles from General Motors, Dodge, and Ford Motor Company. The transmission was originally designed and built by BorgWarner for the Dodge Viper later being used by GM in 1992 for the generation II and later engines, but from 1998 was built by Tremec, though nothing changed internally. The T-56 has been succeeded by the Tremec TR-6060 transmission in many former T-56 applications, as well as applications requiring greater strength than the T-56 could offer.