If you're struggling with how to remove the rear wheel hubs from a Model 20 AMC rear axle shaft, check out my HD video how-to on the use of an OTC hub puller: http://www.4wdmechan...Hub-Puller.html.
There's only one way to preserve these parts and get the rear hub loose...Make sure you mark the position of the hub and axle before removing the hub! "In the day", these hubs were supposed to be tossed out if removed. The knife "splines" are cut into a blank hub with extreme installation torque. Tightening the nut requires huge force to achieve the correct "stick-out length" of the axle shaft from beyond the hub end after tightening.
When folks complain about these hubs "coming loose" on the axle shaft, it's often from repositioning the hub to the axle shaft or from not tightening the nut to create the correct stick-out length of the axle shaft from the hub. I have tightened these nuts with a floor jack handle on a 3/4" square impact socket to get this correct stick-out length—I write about this in my Jeep CJ Rebuilder's Manual: 1972-86 (Bentley Publishers)...The book is available from Bentley, 4WD Hardware, Advance Adapters, Quadratec, Amazon and elsewhere. If you have the AMC/Jeep factory service manual for your model, details on the rear axle shaft and hub are also discussed.