The diagram illustrates 8-3/4″ axles. The top is a 66-72 A-body axle. and the other two are longer axles that generally resemble the B and C body and truck axles. C body and truck axles can be shortened and resplined by a quality machine shop, however it is important to note that not all C-body/ Truck axles are created equally.
The top axle shows that at the location of where the new splines will be (26″ from bearing retaining plate to the end of the axle, see measurement #2 in the diagram) the outside diameter (OD) must be larger than what the OD of the spline needs to be. The bottom axle illustrates how many mid-60′s axles taper as they near the splines, these can not be used as A-body short axle
he Chrysler 8-3/4″ rear axle assembly was introduced in 1957. It is a banjo-type ( Hotchkiss ) axle, ie. the differential is contained in a removable carrier assembly. The axle has an 8-3/4″ diameter ring gear. There are three basic types available distinguished by their drive pinion stem diameter. The 8-3/4″ axle was the primary axle assembly used in most car lines through 1972