First off Dave, you already are off with some facts. BOTH tachs you show are indeed made by Dixco. the 1st tach you have pictured is indeed a Dixco HT/x, but it is definitely NOT an original Yenko faceplate. The Yenko logo is homemade and is not correct, as has already been stated. The "other tach" you post pics of is also made by Dixco, and is a later version of the HT/x. The first one is the correct (for Yenko applications) "1st version", and should feature round bullet-type "push in" connectors on the wires, whereas the second version you show uses regular "flat" wire connectors. The newer version also uses a plastic nut on the bottom to attach it to the hood, where the original version used a steel nut. The second versions I have seen always seem to have the "colored" face, with a red, green, and yellow stripe around the top edge of the face. BOTH versions you show are made by Dixco, and were actually marketed by many different vendors, who often paid to have their own names and logos on the face. Ford, Mopar, JC Penney, JC Whitney, etc. all sold versions of this tach, and all were manufactured by Dixon (Dixco). By the way, What publication are you writing this article for, might I ask? Sounds like Supercarkid already has it written for ya.