Packard V-12 or Lincoln Ignition Rotor??

[Jolly_John]

Hi to all. HOPEFULLY, A PACKARD OWNER CAN SOLVE THIS MYSTERY. I have an ignition rotor I'm trying to I.D. From my homework into an old Neihoff catalog, it seems that my rotor might be an Autolite IGO-1016 that fits 1932 to 1939 Packard V-12 OR an Autolite IGM-1016 that fits 1932 to 1940 Lincoln. The pictures in the catalog appear identical, but two different Niehoff rotor numbers are used, so there has to be a physical difference between the two items. I've attached a photo of my rotor. Here are the measurements that might help in a I.D.:

The rotor I have is 3-1/2" long from the end of one contact tip to the other. The rotor is 1-1/8" at its widest point across. The body is 15/16" high, when measured in the center, from the "deck" of the rotor to the bottom where the rotor mounts on the distributor shaft. The indexing notch or "key" inside the rotor is mounted directly in line with the end contacts, and nearest the contact that is opposite the carbon rod end of the rotor. (Note that this rotor is NOT indexed by having a "D-shape" where is pushes on the distributor shaft. It is indexed by a notch or key that is cast into the inside of the rotor.) The internal diameter of the rotor where it mounts on the distributor shaft is 3/8". Well, that's it, Gang. Thanks for any help. John in Wisconsin