2 or 4 wheel alignment

[guruerror]

Here's a decent article explaining the differences in alignments. http://www.tirerack.com/tires/tirete...e.jsp?techid=4
Looks like a 'Thrust Angle' alignment is what you'd be looking at for the rear.

But I agree with 2010_5thgen...I think you'd really need to beat your truck up before that would be necessary; or have had some sort of side impact near the rear.