I got these axle shafts from an old time racer. He told me they originally came from a 1966 Mustang Group II race car (Trans Am series). The original car was used as a parts car back in the 70's. I got several pieces from him that he said came from the original race car and his story seemed more real when he handed me this set of 31 spline axle shafts. 31 spline axles were only used in the Group II road race cars.
I have seen a few Ford Toploader 4 speed transmissions that were used for racing that had a white stripe painted on them to signify that they were special racing parts. These shafts also have white stripes painted on them along with the faces also being painted white as well. I don't know if this is just a coincidence or if this is in fact a factory marking for a special racing part.
I tried to do some research on these axles, but found very little information. I did find that the K-code Mustang's and Shelby's all used a 28 spline axle. I also read that the R-model Shelby also had a 28 spline axle. The only car that I could find with 31 spline axles was the Group II road race cars.
They have a 4-1/2 bolt circle.
The long axle measures 30-3/16
The short axle measures 26-1/8
The splines look great.
The guy told me he had planned to use these axles in a 1971 Maverick race car he was building back in the mid 70's, but ended up not using them. These axle shafts have sat in his shop for the last 40 years.