Ok, I was able to get a 23" Swan style Gennie shifter arm to replace the short Gennie already on the car. However, the mechanisms are different? The installed arm fits down into the shifter mechanism, secured with a single roll pin going through the sleeve and the arm, the new arm clearly is meant to slip over some type of stub, and is secured with two set screws. What am I missing? Do I need a different part or what? Sorry if this is a dumb question, I did searches but didn't find anything helpful, I plan to ask the vendor, but thought I might get answers here.