9" rear end question

[loudandlifted]

do they make or is there a replacement for my 77 ford f100 2wd. i have a posi rear end with 4.10 gears. well it is for 28 spline axles. and my truck has 31 spline axles. i guess my question is did they ever put the 28 spline axles in the pickups?

 

[blacksnapon]

do they make or is there a replacement for my 77 ford f100 2wd. i have a posi rear end with 4.10 gears. well it is for 28 spline axles. and my truck has 31 spline axles. i guess my question is did they ever put the 28 spline axles in the pickups?

When I rebuilt the diff in my 74 f100 4x4, there was a choice between 28 and 31 spline.