there are adapter kits to use a bmw GS6-53DZ and other variations of manual transmissions for the mb m113
If I remember the GS6-53DZ is the stronger one, or close to it, but they have one that is rated around 460 ft lbs and on bmw forums talking about using it on 1,000 hp cars for racing.
Adapter kit, single piece aluminum flywheel and clutch for about the same price as a oe dual mass flywheel and clutch for our m112 's