I had used a tach adapter for my 3.7 for my window switch when I was running nitrous.. although the tach adapter isn't needed I thought it was made to give you the cleanest tach signal possible
Correct you can still find hellion single kits for sale, but as of now hellion is no longer making them. John urist. (The owner) had told me that the twin kits for the 5.0 were outselling the single kits for the 3:1 or something like that.