I am trying to find a adjustable vacumn advance for a Ford duraspark distributor and some replacements are adjustable,I just happen to have another distributor that does have a adjustable vacumn advance but I did not see a part number stamped on it. I wish every part had the number stamped on it so it can be identified and my trip to autozone with part numbers from the Wells catalog was not sucsessfull due to the system not being able to cross reference or the person not knowing how. I will probably rod the part from the other distributor but I will need to replace it when i work on that project.