The rearend gears that you want are 4.10 and if you count the teeth on the ring, there are 41. The description that I hear over and over is 67 to 72 3/4 Ton with automatic and coil springs. The reason for mention of coil springs is because there were some Danas used with the leaf spring setup. I put one from a 71 in my 51 1 Ton and it cruises nicely at 50 mph, which is what I want with my original 216.