Original GM vacuum advance. Correct original design "MS 373" for 427 L-88 and ZL-1 engines. Fits 1111240, 1111295, and 1111927 distributors. Has original factory OEM "Z1" white marking(See 2nd PIC).
GM calls it a vacuum advance, but it just holds the breaker plate in place. Great condition for its age.
1967-1969 Corvette 427 (L-88).
1969 Camaro COPO (ZL-1).
Listed on eBay starting at $197 and ends Sunday night.
EBay link:
https://www.ebay.com/itm/133609628896
Thanks, Sam