According to my 1966 Bell catalog #YCP is a Mallory Photo-cell breakerless ignition system and when ordering you have to specify battery voltage, ground polarity, make and model of engine. With a # like YC283 guess it could be for a 283? BTW there is no other part numbers with the YC prefix. swifty
best bet is to compare the bottom end (from the intake sealing flange downward) with a stock Chev V8 distributor. If it's not close, then you'll have to stick it in your back pocket and head for a swap meet and started doing visual observations side-by-side. good luck dj