Okay, doing rear pinion oil seal....new seal in place, proper depth, pinion flange on, pinion nut won't go on all the way. yes I'm using a new pinion nut. pinion seems to rotate fine, don't if it's supposed to be tight in the housing or if a little play is normal. I had use a dead blow hammer to get the flange off and on, even with grease on the splines. what am I missing????