The first problem is when you turn any direction the front pass. side wheel squeeks. I looked and did not see anything but I have not gone "in depth". it is more of a "squeek squeek squeek" noise, but only when you turn.

the next problem is the oil leaks. I think its the rear main seal but I cannot confirm this. I replaced the valve cover gasket and that help a good deal. What are some "signs" of a rear main seal leak, and is there any other places behind the engine that would cause a bad leak.

Finally, how hard is it to install a transmission temp gauge on both a 98 and a 00 both aw4 and both 4.0?

 

Sounds like a bad U-joint behind the wheel.

Pull the inspection plate off the bottom of the bell housing and see if there is oil on the fly wheel.
There's only 2 things behind the engine that will leak. Valve cover or rear main.

There are no provisions on the AW4 to install a temp guage. You will have to tap it in to the cooler line or find a way to screw it into the tranny pan.