This is a NOS vacuum advance unit for the distributor for the years and makes listed below. This is a original NOS Mopar part in it’s original packaging.
1958; [see below for specifics]
Firesweep; Firedome; Fireflite; Adventurer with distributor #1779950 [IBP-4005]
D-500; Custom Royal with distributor #1779950 [IBP-4005}