I wired one in on a 1983 countach. I went to checker auto and bought the box and sent it to msd in el paso texas and they modded it for about 40 bucks. msd supplied me with the wiring schematic. A little footnote I ended up having to use a different power wire (one on the alternator) and a different ground than the ones originally feeding the stock ignition for the tach to properly work. It would not work right wired to the stock power and ground. Msd told me this was normal. I think I still have the schematic that they sent me if you can't get one, but I don't know if it will work on a anniversary.
Dave