When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I believe the build date is on the same line as the axle code. It should be a 3-letter code. Mine was extremely hard to read, but I managed to make it out:
I FOUND THE REAR END CODE ON MY '66 STAMPED ON THE BOTTOM OF THE MAIN CASE JUST IN FRONT OF THE REAR COVER. IN OTHER WORDS, IN YOUR PICTURE YOU SEE THE TWO REAR COVER BOLTS AT THE TOP OF THE PICTURE. MY CODE WAS STAMPED IN THE AREA BETWEEN THOSE TWO BOLTS, BUT ON THE CASE, NOT ON THE REAR COVER. (between where the strut bracket mounts and the rear cover)
One day while I was under the car, I went to look for the axle code. I couldn't find my rear axle code where it should have been, or so I thought.... Just for the heck of it, I cleaned the entire underside of the diff with some degreaser, and to my astonishment, I was able to read the code. If you haven't done this, try it. The stamping is very faint, so make sure you have good lighting when you look. Good luck