For a limited time in 1996 only, Volvo offered a new heavy duty manual transmission designed specifically for the 850 R (excluding U.S. market), called the M59, which featured a viscous coupling limited slip differential. Furthermore, the M59 equipped cars were fitted with the B5234T4 2.3-litre 5-cylinder engine featuring a larger TD04HL-16T turbo, re-designed turbo manifold & intercooler, unique ecu with Motronic 4.3, uprated fuel pressure sensor and a heavy duty clutch. These modifications enabled the manual transmission cars to produce and versus and for the automatic transmission.