You can use a GM V6 rodeo cluster as well, but you'll have to adjust the tach to read right if you do

Just some info to be had. I finally tracked down that pesky pot and here are some numbers for those who might want to just drill the hole and not disassemble the cluster.

As is said in Dan's article, the general location is above and behind the tach face. A good place to start would be to drill a small hole 1 3/4" from the side (left, facing the front of the cluster), and 7/8" from the back edge. This puts you just to the inside edge of a lump on the white plastic back cover.

I ended up going with a 3/8" hole, but that is because my small screw drivers have a stubby shank on them. Drill what you need and then seal it up when you are done.

Good Luck,
Michael