Xmember will be a custom jobbie. Depending on the bellhousing, you may need to compensate for a "slanty" gearbox. Most the bellhousings are made for direct horizontal fitting and the 4age in a sprinter has a tilt towards the drivers side to aid oil draining/lubrication. You'll see what i mean when you bolt the engine/box in.
Have them measure the distances for the tailshaft as depending on what bellhousing you have, they may need to make it 2-5mm longer/shorter than someone elses setup.
The thrust bearing should come with the bellhousing or it should at least tell you what's compatible. I've got a dellow housing and you need to use their clutch fork/thrust bearing.
Eddie.