your talkin bout the 540 sport 6 speed? I think I read that its a different bolt pattern on the bellhousing and block but I'm not 100% on this, hopefully someone else knows as I'm planning "sometime" in the future to build a ground-up E24 with things like NO bumpers at all, continuing the nose curve down to a fabricated spoiler, fully worked engine(racing carbs.)maybe even supercharged,etc(a track/show car), the type of car we only wish DOT or TUV would let BMW really make. Never thought about it but a 6spd. would be a great addition!