I did it to the front and rear of my 47 2nd series. The plates aren't welded, but they are riveted with nice big rivets that are hard to grind away. If you do stick with it and get the old backing plates off you will discover the Bendix plates have a smaller hole and don't fit over the flange on a Huck style axle... From what I've read and eyeballed the backing plate mounting surfaces are in a different spots on the axle. What I ended up doing was buying a 51-53 1/2 ton rear axle housing and just swapping everything over. The third member and axle shafts all fit for me. If you have a 47 with the original transmission you need to keep your torque tube since its a different length than the 48-53. If you go this route keeping the torque tube and your third member with a 51-53 housing I don't see why you couldn't keep the 3.55s. Make sure you get the e-brake lever, spreader, and eccentric bolt for the bendix setup too if you go this route.
