3600, I found that I had a bent lower control arm, after I had welded my up. So thats why its so important to have accurate measuring points to start with. I would find a true reference point on the original "rear" section of the frame, make sure it's square and level. Then you can find a true reference point on the subframe to measure to. I wouldn't use the ball joint, grease zerk, because any suspension component can be bent/damaged. I'd also make sure the rear axle is centered/squared up, then check the wheel base. Last resort you can have a local body or frame shop check it out for you, cost anywhere form $100.00 to $200.00 plus extra to repair it.
