Welcome to the wonderful world of the Eaton HO 52 rear axle. No, it's not like a Ford, Dana, or anything other than a Peterbilt or other big rig axle- - - -just downsized. The seal is carried in a cast iron housing behind the pinion ,so once the flange is removed, the seal carrier can be pulled off and the seal can be changed on the workbench by driving the old one out and installing a new one. If you find the pinion nut loose after removing the driveshaft you're dealing with worn pinion bearings, so replace them along with the seal. The design of the rear end allows the pinion and its bearings to be removed from the front of the housing without disassembling the rest of the axle. If the pinion bearing is the double ball type, just get the nut tight- - - -there is no preload adjustment required, and no crush sleeve. The double tapered bearing design needs shims and a preload procedure- - -check a service manual for the proper procedure on that one. I doubt that the 56 model axle will have tapered rollers on the pinion.
Jerry
