45 degrees of rotational play is not bad. From the sounds emanating from your birfields, they do need a repack, however. Might be the first time for them, in which case they're long overdue.
I think you are right about the repack(160k+ miles) the movement is rotational, all tires on the ground, out of gear. 40 degrees(almost a 1/4 turn) before engagement of axles or wheel movement. Like I said, im a bit intimidated by the prospect of going into the axle, but I will probably grab the DVD on Birf replacement. Couldnt hurt. Wish me luck. and sorry about the thread hijack