I'll be doing a swap from 2.73's to 3.42's on my truck and have a couple of questions . First off , I need to find pinion depth , I have a couple of ideas on how to measure from ring carrier center line ... These ideas involve machining (I have a quite complete home machine shop) a shaft with a flat spot and discs at both ends to center it in the bearing cups . Is there a tool I can copy or am I on my own for design ? Another question is how to lock down the pinion shaft when checking gear lash ? I'll be using a spacer sleeve and shims instead of the crush sleeve so that part is fairly easy . I have most of the tooling needed , what I don't have I can make in the shop ... but for some of these things I need a sample to copy . Right now I'm wishing it was as simple as when Dad re-geared the '59 Merc ... Unbolt one chunk and bolt in the other , slap the axles back in and roll .