I have a 1969 chevelle SS396. I'm switching from standard idiot lights, to gauge and tach cluster in the dash. Wondering if someone can guide me with some steps or where to go for instructions, and do i need factory harness too? Thanks for your help.

Check out Noneck's (http://www.noneckschevelle.com/)

Select "Tech Tips" then "Converting '69 Chevelle idiot lights to guages"

It's exactly what you need, excellent info. Wire the amp/battery gauge as shown in DIAGRAM #1 not as shown in "PHOTO #3

Just looked at the site. Great info!! Thanks again...