The center pin in the sure grip I guess you installed all the way and tight, you had a non sure grip and 489 type in there prior. It was a square block. So it had a floater type. The axle was adjusted to that other one before. So it sounds like you need to first install and tighten the non adjusting axle all the way, then, loosen the adjuster on the other axle , install it, tighten the 5 bolts, then adjust the end play. Did I explain it good enough?