I hooked up a gauge set for my bird Thursday. I was gonna use the plug by the dist but I couldn't get the bugger out. I thought it would be 3/8 but no. I ended up just putting a "T" by the sending unit for the idiot light. All in all it was easy and it sure is nice to know the oil press & temp. I also have a manifold vacuum gauge that the PO installed under the ignition key. It looks like 70's vintage and it says Pontiac on the faceplate. I took the time to repair it since I was working on gauges( small obstruction in the inlet ). I had to replace a couple of bulbs and now all my dash lights work and dim properly.