[BlackChevy]

Okay, future reference for anybody else who may be doing something similar to what I'm doing:
After some looking and over $500 later, I did a side-by-side comparison of a C10, C30, and C60 Chevy truck cluster. The printed circuit on the back of the C10 and C30 was identical, so if you're swapping a C10 non-tach cluster for a C30 tach cluster, the harness will be the same. You'll need to look and see if you have the same light indicators in the gages - if not, just swap out the light filters. The tachometer will need its own wiring. The C60 (tach with gas gage built in) is different, but only because its missing the leads for the two lamps that would have been in the tachometer. Instead there is a small gas gage there. The missing leads in the printed circuit go to leads 13 and 17 on the harness, so you could regain those lights by using a splice connector and running a remote light cluster like Corts60 has pictured. I don't know what to do about finding a light cluster like that though, I just looked on eBay and found the information center from a Mazda, and plan to just cut out the lights I need from it and somehow make it look right on my bezel.

I hope this gets put in a sticky or information post somewhere so somebody else doesn't have to spend so much money to find this out. I could not find anything anywhere that would come right out and say what will work and what the differences are or how to deal with them.