If all you want is the center section, you can cut the drum just to the outside edge of the flange so you can remove the outer part of the drum. Then remove the brake shoes and use an end wrench to remove the nuts that are holding the axle bearing flange in place and pull the axles out like you would the normal flanged 8 3/4 axle shaft. Before you trash the old axle shafts, be sure any pinion spacer that might be in the center section doesn't stick to the old axle shafts.

You will want to test fit the axle shafts from the rear end you want to use the older center section in to be sure the later model axle shafts have the same spline count as the older side gears.