If you want to put a medium duty trans on the back of an IDI, you need to find an trans adaptor from an IH medium duty truck or an IH bus with an 6.9 or 7.3 IDI in it. May find one at a scrapper that buys those kind of vehicles. You can find them on eBay from time to time. You'll likely need the flywheel from one of those applications as well as the input shaft will have a larger pilot bearing size than that found on light duty trucks. The clutch will have to be for a medium duty and the clutch linkage will need to be sorted out as well.
Not seen it done before, but, it can be done with the right parts and a little fab/modification.
Please post up some photos. Might want to check out oilburners.net as well. A ton of IDI stuff there.
Heath
