Thanks for all the info, let's kill this thread and move on. I have the stock tire and rim package for an SR level Montero, that is, 31" tires, 15" alloy rims and 4.88 gears from Mitsu <img src="/forums/images/graemlins/cheers.gif" alt="" />. I think the control arm bushings are probably at fault and will recheck them this week. As for weak shocks and cupping, yes I really agree, worn struts and shocks can contribute or allow cupping to happen.
Thanks again for all the inputs and posts, it's rare that I get stumped by my own truck, but we've all been there. <img src="/forums/images/graemlins/kewl.gif" alt="" />