Yep, sounds about right. Until recently, I was a Chrysler tech. and worked on a few diffs during my time.
Fortunately we did not have to deal with a dropout center in a vice since almost all the recent RWD Chrysler products have a Corporate/Dana style housing. Generally we rebuilt them with the vehicle on a lift with the housing still bolted to the car. To crush the sleeve, we used a long pipe over a bar like you did, probably about 6 feet long.
Those things take an unusual amount of force to crush, sometimes required two guys. I will admit to re-using an old crush sleeve once or twice.
Do you have a yoke holding tool? Didn't see you mention it. I would think you would have had to have one to do the job. You put it over the yoke and turn it until the holder handle hits the lift arm or part of the frame, then you pull on your bar. Not sure how to facilitate that operation with the diff in a vice. Maybe have the handle against the floor.
