Just connected the posts .If the rear axle is from a 55 first series truck it would be a 390 ratio rather than a 411 ratio like the torque tube .I don’t know if the spring perches will line up maybe someone will know on here ..The Sm420 transmission will need the rear cover we’re the ball is attached replaced with the matching yoke and speedo gears should be close to swap.Then a driveshaft and u joints to make the truck open driveline..This may be a option to compare with just replacing the backing plates as once you take the torque tube brake drums off you may see that the axle seals are leaking and question is it from the bushing and seal in the tube that will require more work .
