The ZF S5-31 transmission is a five-speed manual transmission by ZF Friedrichshafen. The transmission is designed for use in longitudinal engine applications. The transmission is rated for 310 Nm (229 lbf ·ft) of torque. The transmission weighs ~39 kg (86 lb), and holds 1.3 litres of transmission fluid.
Using different bell housings, the transmission was fitted to many different BMW engines.
ZF S5-31 transmission Wikipedia
The ZF S5-31 transmission is referred to as "S5D 310Z" by BMW. The transmissions made from September 1995, were made with a reinforced design and are named "S5D 320Z", and is rated for 320 Nm.
breakdown of the old BMW transmission designation1995–1999 E36 328i
1992–1999 E36 M3
2001–2006 E46 325xi
2000–2006 E46 330i
1990–1992 E34 525i (M50)
1992–1995 E34 530i (M60)
1996–2000 E39 528i (M52)
2000–2006 E53 X5 3.0i (M54)
1996–2000 Z3 3.0i (M54)
1996–2000 Z3 M3.2i (S52) *Canada & USA only
1996–2000 Z3 M3.2i (S54)