Wheel aglinment problem...

[96two-door]

Hey everyone
Looking for a little help, I have a 96 door Tahoe stock suspension and I'm having problems with getting the truck to track straight down the road. Took it to sear auto and had them do a wheel aglinment go back out and its still pulling to the left. Took it back and they told me the rear end thrust angle is off and is not adjustable on the truck... I measured it one side is about half an inch forward of the other. Anyone know what to do with this, I've never messes with adjusting a rear end before.

[bowtiefreak]

The pins on the leaf springs center the axle, check there first to make sure one has not shifted in any way

[96two-door]

is there a way of checking that without unbolting the rear from the leaf springs?

[96two-door]

I visually inspected the rear end this weekend...The pins are still in place and there are no signs that suggest the rear end moved around on the leaf spring. I did notice that the bushings were split and starting to crack, wondering if maybe that could cause the rear to be off??