Have been working on this off and on for about 6 months. Got some help from the boys over at Moparts and after collecting lots of original photos of stampings and looking at the original axle stamps I have here in my shop I came up with a set of axle numbers and letters. No stock font match perfectly so I ended up making my own. I starting with Cheltenhm BdHd BT and fixed some things so it was a better match. I ordered some stamps to test. They look fantastic!
I made small changes to the Cheltenhm BdHd BT font to account for the wear and over use an original stamp would have had. The set of fonts I built has .02 contour so they look more correct (accounts for the wear and normal use the factory font would have had). Also, some fonts (like Cheltenhm) have larger numbers (compared to the letters) designed in to them. So I also adjusted the letters so it matched the factory and the numbers & letters are consistent. Overall it's a super nice match. Best I've seen so far. Here's a photo of the done set of letters and numbers.
Email me and tell me what letters and numbers you need for your project and I'll set them up in single JPEG files so you can have stamps made. My email is codyreich (the at symbol) comcast (dot) net. I used
http://www.rubberstamps.net/Art-Stamps.aspx and they did a nice job for a really good price.
Hope this helps. Good luck and please feel free to share these with anyone who wants them. It's good for the hobby.