If you want a core, I've got one sitting here already disassembled, cleaned and waiting to be rebuilt. I'm going to do the swap, but I've got another little one on the way and we'll probably be moving in not too long so It's just going to continue to collect dust for now, and in any case I can get another one later on. It's a 4wd unit complete with cover,dipstick, TC flange, and all the parts...really only needs a basic oem rebuild kit to get going again. I'm a straight shooter, BidDaddy can attest to that, so if you're serious I will help you out. This offer goes for anyone local on here, as I'd rather help someone out on the forums than try and sell to Joe Schmo on Craigslist.

 

Any will fit, but 99 up have the extra top bolt hole for the LS based engines. It's not needed, thus many use earlier cores. The 97 up seems to be the preferred case though, and slight changes have taken place over the years which a good rebuild kit will address with the updated parts. At a minimum, you need to pull the pan and check the fluid.