The 3/4 ton rears typically had a 4.56 ratio in them, as stock/standard from the factory. The 4.11 wont gain you all that much more in the speed department, and there may be issues with '70's vintage carrier (open driveline) being fitted into a 1950, that, if original, should have an enclosed driveline. You'll likely need to swap a newer tranny in as well. HTH
