Okay. So I'm a cheap bastard and want to put a tach in my 99 5 speed cavi. is there a wire I can tap into for hookup or do I need to buy the adapter?

I don't know how to add just a single gage but you can always swap the entire cluster for one but you will need to find one of the specific 99 digital ones. There were some late 98 digital ones as well but I think that the fuel gage signal was different that year and won't work correctly. I did this cluster upgrade for my 99 and it gives you a better thermometer vs. the standard range from "C" to "H". I bought my cluster for about $40. Even though it was for a 4-speed it worked fine with my 3-speed. It would probably work fine for a manual though you would have the extra gear indicators on the bottom. There should still be some MT clusters on ebay for your 99 though they they are less common due to the uniqueness of that year.

If you just do the cluster swap, your odometer will change. My cav suddenly gained 30,000+ miles when I did that with mine. (I took both cluster apart and tried to change the odometer display board and the display but it did not keep my older mileage. It must be stored on some other part of the cluster for them) I don't think that anyone cares if your Cav gains miles but it could be dodgy the other way around.

99 and the late 98 Cavs with the digital odometers as a whole have some odd things about them that are unique just to those years. They were transitioning to the major changes for 2000 and beyond. I suppose those were interesting times in Lordstown.

Good luck.