I doubt the 4.11 Eaton was ever factory installed in a 1-ton though I suppose its possible. The axle and differential design was used for many years in both 3/4- and 1-ton trucks ending in 1972.
More important than getting a specific Dana axle would be finding an axle the right width and with the gears you want. Since you are dealing with a 3/4-ton a Dana 60 is probably strong enough but you'll also see Dana 70HD and 80 and GM 14-bolt axles and maybe things like the Ford Sterling.
The Dana has been used under pretty much everyone's truck at some point in time and is likely to be the easiest to find. Because these things are heavy you don't want a bigger one than you really need. Because not everything its been used under is 8-lug you'll want to confirm that too before buying.
