The G50 is actually a transaxle type used by Porsche, and 911's from that era (late '80s perhaps into the early '90s, I think) are often referred to by the transaxle which was a desirable high capacity unit used in the Turbos, among others.
The G50 gearbox was first introduced in 1987 in the Carrera 3.2, only appeared in the last year of production in 1989 in the 930 turbo and then went onto use in all the 911's ie 964,993,996 and 997.
