Hot Rods Ford V8 Rear End???’s (part 2)

Seems like the 1936-1941 rear end is the width (59 1/2” WMS-WMS) that will work the best in a 31 A with stock fenders, 35 wires and Coker 7.50 tires. Other than the improvements from mechanical brakes to hydraulic brakes, are there any other things that are different in that run of years, bearings, gear strength ect.? Car will have 283 39 trans. torque tube.
-Thanks

 

35-38 had 12 tooth spiders and 18 tooth axles. 38-41 had 11 tooth spiders and 16 tooth axles. Not sure why they changed or if one is stronger? About the same time the pinion to driveshaft coupler changed from 10 spline to 6.