Ford 9" Inch Posi Traction Rear End Differential. 10 Bolt, 28 Spline, 3.25:1. Information tag on rear differential reads WFB-C2-1KD 3L25 9 957B. I went through this rear end with my mechanic to use my 1967 Cougar that I am working on, but decided to go in a different direction. It has been cleaned, inspected, painted, and bearings replaced. It has a great gear pattern and is ready to drop into your vehicle or modify to your specifications. We measured the housing when it was completely disassembled and the housing is 55 3/4" from bare flange to bare flange.