[Mike C]

Call Randy's RIng & Pinion and order old school on the phone, but I think they are 30 spline. But my reason for posting is to suggest if you are serious about performance, ditch that drum front and get a later model disc brake setup. The late 72 and up have larger u-joints in the axles, definitely something you are going to want with a front end traction device, and the open knuckle axle steers a BUNCH better.