I've seen this axle, and I'm all but sure it is a Dana 80. (I was sure before this confusing number stuff.)
It's got 4" round tubes, Dana on the cover as well as the typical Dana cover shape, and it appears to be a larger housing than a 70HD. It certainly has larger disc brakes than a 70HD.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-