Well, thinking about it, that is probably one of the most straighforward swaps of its kind. 4BTs were used in vast numbers in bread trucks. Lots of these had 400 turbos already in them. Bolting it to the M1009s 400 turbo is a non issue. Only real task that remains is the engine mount fabrication. All that would remain is the little stuff like figuring fan spacing and radiator hoses. I know we won't hear from him until after Aberdeen but probably our best source of info on this will be Cabell Garbee. Oh to have a spare 4BT.