What all is needed to do the swap and how hard would it be? The 5.7 in it now has alil over 300k and is leaking oil so just wanted to know how hard the swap would be.

 

Pretty sure ther are a few write ups on this. Just search for it. Fairly straight forward. Just find a good motor with harness and PCM. Just got to change a few things on the harness, rid of vats in the tune, get you some engine mount adapters and voila. It is a little more involved than that lol! But, you get the picture. I think you may have to do something with the a/c because it may hit the frame rail.

 

Here is what I found in my search for 98....
http://www.hotrodlane.cc/PDFFILES/Lisa%20Tahoe.pdf