Not quite as easy. The front and rear differentials are different size. The rears are an 8.5 inch ring gear with the front a 7.5, if I remember correctly. The differential out of any 4-cylinder D50/MM will fit, as will the ones out of the early Monteros/Raiders. The V6 trucks may also use the same size, but I'm not sure, they may have used a slightly larger one. If you wanted 3.55 gears, assuming you can find a truck with those in it, they should swap over no problem in the rear.