If you have the Eaton axle it is possible to remove the complete center section and replace it with the 4.11 geared differential from another truck. Provided you can find one...
My one caution is to make sure you have an Eaton rear, and not a Dana before you start this swap. The 'round pattern' suggests it is an Eaton, the Dana would never be described as 'round'.
The 4.56 and 4.11 are not the only options with this housing. There is also a 5.17 that was optional in 3/4-tons and standard in 1-tons.
