I just did a search on this topic but I did not find a clear cut answer. I want to install a factory tach in my 69 and I will soon have an HEI. Can anyone tell me a yes or no for sure. If it yes could please explain how it wired. Thanks for your help!

The wiring does not change. The factory tach will install exactly as it would with a points style ignition. The brown wire connects to the neg. side of the coil, or to the connection labeled "TACH" on a GM HEI distrubitor.