my jeep has 4.5" lift and my 4wd works fine but when i flex it there is a popping sound the like a weird sound that seems like something is spinning do i need a sye? or would rustysoffroads long travel yoke fix my problem?

 

Doesn't sound like either to me. With a 2000 xj at 4.5 inches of lift you should have a sye anyway. I would check all u-joints first. then check under your jeep to see if anything is hitting when flexing. This should be fairly obvious as paint would be missing or there will be visible damage. The extended yoke you are thinking about is not worth it. A 2000 has a different t-case than earlier xj's which generally requires a SYE around 3" of lift to eliminate drive line vibrations. If an SYE is too expensive at the moment try a transfer case drop. They are sooper cheap and extremely easy to make
http://jeephorizons.com/tech/tcasedrop.html

Good Luck
-Mike

 

A sye was the best investment I ever made on my xj, a little pricey, but definitely worth it even if its not the problem.

 

t-case drop on a 00 or 01 is a bad idea. the front is a low pinion so the angle is pretty harsh already with a 4.5 lift. when you drop the t-case it will make it even worse. SYE and maybe think about a high pinion d30 if you go any higher