Outer Limits 4x4 Board

Can someone help me out and answer a few questions about torsion bars?
It seems my torsion bars have sagged on my D21 navara, so i want to raise the front back up to match the rear.
When i looked under the car, the torsion bars are at completely different adjustments - is this normal? One of the bars has almost no adjustment left and the other one has about half of the thread left!
I have been doing a bit of reading on this site and have found that on some cars you can 'reindex' the torsion bars to put the bar back into the right range of adjustment - can you do this to D21 bars?
If not i suppose i'm looking at a new set of torsion bars, what would these be worth roughly? can anyone recommend a good brand?
Torsion bar suspension is all new to me! Hopefully they aren't too diffficult to remove/install/adjust! Any tips would be great!
Mark.

Reindexing is no big deal. Just lift the truck on jack stands so that the front wheels are off the ground, loosen the adjusters on both sides completely until the nuts are just holding on half the thread, next unbolt the torsion bar anchors on the other end of the t-bars (lower control arm) and slide anchors backwards off the splines. Now you can re-index the anchors by turning them slightly and slide them back on. Adjust the t-bars to the desired height and have the front end aligned.
Beware that the t-bars might be worn out after around 160k km's anyway. I suggest replacing them with Tough Dog or Sway-A-Way ones while you're at it.