Just a note to what Pat said. The Lincoln Marks, late 70's types, have some huge axles that can be cut and resplined quite nicely.... They are also quite wide, so most narrowing jobs will get into the big part of the axle so they can be resplined..... Oh yeah, a lot of them came stock with disc brakes, too.....

A lot of the older passenger car axles are just to thin to be resplined but the big Lincoln ones can easily be cut and splined to 28 or 31 splines....