[compsur]

Hey Mark, sorry for not getting to you back sooner. In 67 they originally published 2 temp switches and 1 sensor as far back as the 69 parts book. 1st, no Rally/no ATC , 2nd ATC/no Rally and 3rd no ATC/Rally gauges. Eventually or by 71, the 2 switches (1 and 2) were superseded into a single part number. Studying the wire diagrams which included motor harness for ATC or non ATC, the ATC harness itself and the Interior Rally/non Rally harnesses, the key wire differentiator for both the idiot light and temp gauge is the dark green wire. The dark green wire can be found leading from the temp gauge to the temp switch. For ATC cars the motor harness has to be changed to an ATC harness which has a light green/black stripped and dark green wired connected to the temp switch. The light green/black striped wire is specifically for ATC, won't be found on non ATC cars. I pulled the manifold and had a second hole drilled for the temp sensor on right front water crossover on the manifold, in 67 you can see a flat riser...seems they may have anticipated another switch or sensor in this area. I took the dark green wire out of the 2 wire connecter that connects to the current switch and connected it to the newly installed sensor. I just tested it and it my rally gauge is working perfectly. As I mentioned i studied the many wire diagrams and couldn't find any correlation with the dark green wire and ATC system. I could be wrong but both my ATC system and now my temp rally gauge are working perfectly. Let me know what you come up with. here are some pics.