It sounds to me like you have twisted splines in you side gear, time for some more carnage maybe major, get a real big slide hammer and just keep going at it untill the side gear breaks or get a chain with a couple of large washers to go on the end of the axel, some ear plugs, a friend to hold a pipe or bar on the chain and hit it with a 12lb sledge hammer where the chain meets the bar or fide something real heavy and use that but make sure to tie your rig down first.