Dana's had a 3.54 or a 4.10 ..Noted on the metal tag..They didn't have all the war paint an 8-3/4 has (unless Dream Car Garage did the resto). The date codes (and other info - see below) are hard stamped into the axle tube.

Bill of Materials Numbers:
68-69 B body 3.54 Powr-Lok 602957-1, -2, -3, -4
4.10 Powr-Lok 602957-5, -6
69.5-70 B body 3.54 Powr-Lok 603109-1, -2
4.10 Powr-Lok 603109-3, -5
4.56 Powr-Lok 603109-6, -7, -8
70-72 B body 3.54 Trac-Lok 603222-1, -2
4.10 Trac-Lok 603222-3
4.56 Trac-Lok 603222-4
75-77 B body 5.13 Powr-Lok 603347-2
5.38 Powr-Lok 603347-1
69-71 E body 3.54 Powr-Lok 603080-1, -2, -4
4.10 Powr-Lok 603080-3, -5
4.56 Powr-Lok 603080-6, -7
70-72 E body 3.54 Trac-Lok 603226-1, -2
4.10 Trac-Lok 603226-4