If you have blocked the runner in the heads, or the crossover and have lost your choke, this may be what you need. I use parts from other early Rochester carbs to mount a choke cup (same as 59 to 65 center carbs) where the pull-off would have mounted. I modify this the cup to accept vacuum from the same source on the throttle body the 66 pull-off uses. You do not have to remove the 66 choke shaft. This is a bolt-on. All screws, gaskets and parts you need are included. No need to remove carb to install. Electric one wire choke insert is new. E-MAIL ME BEFORE ORDERING AS AVAILABILITY IS LIMITED. Guaranteed.