you may not be happy long term having an m47 in a turbo car. this transmission is NOT able to handle heavy torque from the turbo according to this informative site.

http://people.physics.anu.edu.au/~amh110/Supra/supra_in_volvo_240.htm


WHY GO TO THE TROUBLE OF CHANGING - VOLVO GEARBOX BACKGROUND:

Volvo M46 with Overdrive: The 240/760/740 Volvo turbos use a strong M46 gearbox being a Volvo in-house designed 4 speed, and bolted to it is a UK designed Laycock de Normanville Overdrive gear assembly for 5th. gear. Early M46 transmission cases where cast iron, later cases - Al.Alloy. The gearbox is reportably good for near 220 hp levels with a torque load of 220-295 ft.lb (300-400 Nm). Around 1986, 740/760 turbo models came fitted with a slighty updated M46 'D' box mated to a tougher 'Type P' Overdrive. The 'Type P' could handle more torque than the 'J', the main change being an increase in the M46's output shaft diameter, hence later 'Type P' OD's cannot be retrofitted to the earlier M46's with the 'Type J' OD.

The two-section transmission is fine until the 'complicated' Overdrive section causes trouble, being very expensive to replace, recondition, or repair perfectly. Owners face high cost again when it's time to replace or re-condition the 4 speed main gearbox and this is where I drew the line. The gasket sets alone were sending me broke in the quest to eliminate fine oil leaks from the thin ATF fluid.
I wished for 5 real gears based on a strong design at a reasonable price.

Volvo manufactured a 5 speed M47 (versions I & II ) only fitted to NON turbo models (except 940SE low pressure turbo), and hence for performance driving with a turbo engine, the M47 is just not strong enough, one problem area being the breaking of low friction synchros. The internet has lots of M47 information.