I finally found a knee knocker tach for my '66 Chevelle SS 396. It's an NOS and never been wired. I don't have the harness and I was wondering if I really need one? If not, I could sure use some advice on getting it hooked up. Also, I'm not exactly sure of the proper location for mounting and I can't find any info in my books. Judging from the bracket on the top of the tach, it appears that it's necessary to drill 2 holes. Is that right? Thanks in advance for any help you can offer.