Is your steering wheel perfectly centered?I have a similar issue. My LJ pulls pretty hard to the left. Got new tires recently and it still pulls left (regardless of moving tires around). It's a firm pull regardless of road crown or completely level road. Alignment shop aldo recommended an adjustable ball joint. My LJ used to drive straight with no pull for 50K miles. Logic tells me something else must be the issue and an adjustible ball joint is just compensating. Have not figure it out yet, though.
