OK, just found out where the small diameter shaft came from. Am in the process of putting chokes on all the rest of my Holley carburetors because with today's gas it's too durn hard to start my cars if they've been sitting a while. I have two 750 vacuum secondary carbs, one 650 double pumper and two 750 double pumpers. They ALL use the larger shaft except the 750 double pumper on my 59 Dodge. It has the small shaft and a choke plate that screws on (others snap in). Haven't tried to figure out when it was made, but am thinking it's an older version. In any event, fortunately I saved the small shaft and the choke plate for that carb, so it was simple enough to put it back in.
I continually am surprised that things I assume will be the same aren't. (Besides Holley choke shafts, I recently discovered that accelerator pump pistons for Carter AFBs and Edelbrocks are different. Whodathunk?)
