The PL code on the differential says it's a Detroit built axle, RPO 205, which would be a 6.17 ratio.
Here's a couple excerpts from the 1946 Truck Vehicle Information Kit (with highlights)
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
