The only place I have seen &quot;needle&quot; bearings in the 550 rear end is on the bevel pinion and in the countershaft within the transmission.  None of the manuals I have show &quot;needle&quot; type bearings in the axles, bull pinions, or differential. From what I can see in the rear end that I have apart, those bearings are all roller or ball.
I'll take a look at my two 550 rears and think on this.