Im pretty sure if it needs adjusted then the bushes are worn causing the miss alignment only way to get it back is to replace the worn ones. This is what I was told when mine was just acceptable when i got the alignment done. Im going for poly all the way on mine.
When you speak about alignment, are you talking about aligning the rear axle with the front - so there's no crabbing?
If you are, then the rear axle should be perfectly aligned assuming all the bushes are in good condition.
However, it is possible to correct misalignment (if necessary) by making adjustments to the thickness of shims on the tie rods which connect the rear axle to the chassis. There is a large round bush at the chassis end which has a round supporting plate (approx 5" in diam) and shims can be added here.