I am getting a 73 chevy half ton on the 15th. I am having no luck with searches on this , is there a code stamped somewhere on the axles to find my gear ratio and diff type? The rear is a 12 bolt - the front is prob. a 10 but I have not crawled under that end yet.

Look in the glovebox, sometimes the RPO codes are there. It will tell you if you have some type of posi and what gears. The rear will be a 12 bolt, the front will be a Dana 44. The RPO codes can be under the hood, too.

If your real lucky, The tage will still be on one of the top diff cover bolts stating the ratio. If its not in the box, You might have to drop the cover and count the teeth to be totally sure.