or have a Z bar.
Z-bars - especially home-made ones - are notorious for collapsing under heavy loading. A quick inspection of the Z-bar draglink, which connects between the pittman arm and the tierod, would reveal the damage, though.
MY bet is with mrfuelish's diagnosis except that it might be easier to
1. remove the draglink at the adjustable end,
2. center the pittman arm so that it faces directly forward and the steering wheel is correctly positioned (so the turn signals work!)
3. point wheels directly forward (align the tires with the flares/body)
4. adjust the length of the draglink until it fits onto the tie rod or pittman arm (whichever end that you disconnected)
5 bolt it back up.
Hope that this helps!