Guest 2403 Battery Isolator 70A Alternator Negative Ground - Used

Guest Model #2403 marine battery isolator, made in the USA (Guest Corporation, Meriden, CT). Application: DC charging systems using a diode isolator to charge two battery banks from a single alternator — the OEM label specifies negative ground systems and use with a 70 amp maximum alternator. Commonly found in inboard marine engine rooms, generator sets, and similar 12V installations; exact vessel/engine application is not verified. Condition: used take-off, untested. The finned aluminum heat sink and stud terminals are complete, with surface dirt, light corrosion on the terminal hardware, a weathered but readable data label, and attached cut cable pigtails. No electrical or load testing has been performed, so no operational claim is made — offered as an untested used unit or spare. Buyer must confirm fitment by part number, photos, dimensions, engine model, serial number, and application before purchase. Used marine part sold as-is unless otherwise stated. No returns on electrical, used, special-order, or installed parts.