[gmachinz]

Here's what I did-using my existing unmodified cluster plug-in on my 78 K20 I had at the time which had gauges and a brake light indicator, I dropped in a 79 C60 tach cluster and instead of using a BRAKE indicator where the vacuum gauge was which is independant of the C60 printed circuit, I installed a factory clock in its place. So I ended up with a factory clock and a complete, working C60 tach cluster. No repinning was required.....I just plugged in my existing instrument cluster plug-in and it all worked. Since you have electric gauges being an 80, you can use any C60 tach cluster from 77?78 and up. I'm not sure what year the big trucks went from mech. to electric oil pressure. Usually, 60 psi is electric, 80 psi is mechanical. Hope this helps more than confuses....lol.