Here is a search I did of FW Balancing.
PeachParts Mercedes ShopForum - Search Results
Before you remove the auto FW, see if there is any type of mark on the Crank and FW. If not, you could use a small chisle or punch and mark the crank and FW begore removal. this will give you a reference point.
Have the Auto FW checked for balance. then have the Manual FW checked for balance. you will have to have the Manual FW matched exactly as the Auto FW is. Put a Chisle or punch mark on the new FW (Manual) in the same balance point as the Auto one. then mount the Manual FW to the same reference point.
I took mine to a Hot Rod Speed shop that had the balancing equipment to check them here in Santa Cruz.
The longer Driveline front section of the two should be the 240D drive line? If so, use the 240 front piece, and have it shortened. Don`t have the front section of the 300D lengthened.
The rear section of the two should be the same length.
Have a Drive Line shop do this for you, be sure to give them both sections. they will give it back to you balanced, and should replace the centering Bushings in the ends. I had them replace the center Support bearing. think the total was $300.
Mount the new balanced FW. Torque the Bolts.
Install the Pilot Bearing.
Install the Clutch Disk and pressure Plate. use the alignment to line up the splines of the Disk with the Pilot Bearing. then tighten the PP Bolts.
Place the Release/Throw out bearing in the Bell Housing shaft and the Shift Fork.
Install the Transmission, and tighten the bolts.
Be sure to Measure twice, and cut once on the Drive Line. It is usually 4 inches that has to be shortened. Did I mention to measure Twice???
That`s enough for tonights lesson.
Charlie