everything has to be changed to go HO. HO and Renix share a similar setup, but do not share any parts. Chrysler redesigned everything.
What do you gain? not much. unless something is wrong with the truck you have. some of us have annoying corrosion issues in the harnesses. some bought severely neglected trucks. In those type of cases, starting from scratch is a promising prospect.
But if you're up to the task, it's mostly bolt-in. there are some hiccups with the fact that XJs and MJs don't share much in the rear. But nothing that hasn't been solved already by others. :thumbsup: