It depends on what style sure-grip you have. The cone sure-grips and stock 489/741 open cases are going to be a PITA.(not sure about open 742 cases) Just a couple weeks ago I tried removing the thrust block from an open 741 case. I tapped out the roll pin and tried to remove the shaft so the thrust block would come out. The shaft hits the ring gear. I guess the ring gear needs to be removed first. Luckily I did some measuring and I had just enough clearance so I could mock up the rear end while leaving the thrust block in place. When I rebuild the center section, I'll remove it for good.

If you have a clutch style sure-grip, you should be able to remove the button with a punch.