Just wanted to update, the 74 bulb is the right size for the small instrument lights. I'm working on making a detailed writeup of the process (I know there already is one, but this one is going to me more idiot proof for people like me.)

One problem though, I put everything back together, plugged all the connectors in behind the cluster, and No tach or speedometer (and I'm assuming odometer is out too). Any idea what could cause this? I took it back out and made sure all of the connectors were clean and snugly connected, but they still don't work. All of the lights work (Even some of the bulbs that I didn't change work now (the A/T gear lights), but the gauges don't...