Offered is an NOS Autolite VC-1039A distributor vacuum that has been calibrated to be an IGS1023S unit. This can be converted back to a VC1039A by removing the plug, spring, and gasket, ( see last photo for calibration procedure for the VC1039A vacuum. Also see catalog photo for all general applications. Please contact me to confirm a specific application if unsure. This may not have the original box, and finish has darkened on the neck, but vacuum is fine. Item comes as shown.