I'm doing the same swap, what adapter for the driveshaft are you talking about?? I figured thay made a bastard u-joint for the swap, haven't checked into it yet..
Take a look at the Explorer 8.8, it has a flat plate adapter for the yoke instead of the usual round saddle. you can either buy the conversion yoke for the usual round one or take the plate adapter off the donor trucks driveshaft.