Big bearing 9'' measurement

[UrbanRedneckKid]

My search came up empty, though I've seen it somewhere.

There is a measurement of the bolts at the end of the tubes, behind the brakes. I need to know what that is for the EB big bearing 9''.

Also is the EB bb 9'' a 31 or 28 spline axle?

 

[AKBroncoII]

It will be 28 spline. Bolt spacing will be 3 1/2"x 2 3/8" with either 3/8" studs or 1/2" studs.