The part number C6ZZ-10850-A is the original factory Ford specification for the dashboard ammeter / amp gauge used on a 1966 Ford Mustang.
 
A direct-fit aftermarket restoration replacement from Rytech (or listed under a similar "RY" replacement parts catalog) drops natively into the 5-gauge round instrument cluster design used across standard, GT, and Pony interior models for the 1966 model year.
 
Part Overview & Details
Component: Ammeter / Amp Charge Indicator Gauge
Design/Aesthetics: Exact reproduction featuring the factory-correct white lettering on a matte black background, marked with standard "C" (Charge) and "D" (Discharge) hash indicators, paired with a matching red indicator needle.
Electrical Connection: Features the correct post connections on the reverse side of the casing to accept the vehicle's original under-dash factory wiring harness loop