I recommend you get the numbers off your transmission and rear diff and make sure what you've got. That will help you find out if the transmission you have will match your 261, including the flywheel and starter. Another question is what happened to your stock motor mounts when that 283 was installed? Patricks Antique Trucks is a good slource of information for engine swaps using a 261...and they have cool parts. Call them at 520-836-1117. FInd out what your tranny & rear diff are before you call.