This high output alternator features late model 6-phase hairpin stator technology in a custom machined housing that bolts directly in place of the antiquated 11SI design. Don't be fooled by cheap re-winds advertised as making 150-200 amps in the original 11SI housing! Our 11SI upgrade has (12) huge press fit diodes, instead of the (6) small diodes used in a standard 11SI. The MechMan 320 amp unit has twin, solid copper rectifier plates with 200%+ more surface area to dissipate heat, as in comparison to the 11SI aluminum rectifier design. Hairpin stator technology allows this unit to crank out much more output at idle than anything 11SI based, over 120 amps at engine idle RPM! This alternator is certified to meet or exceed SAE J1171, ISO 8846, and USCG Title 33 standards for ignition protection. Simply check the technical drawing in this listing against the measurements of your original alternator to verify fitment. All MechMan marine alternators are made in the USA, and feature a 1 year limited warranty. MechMan marine units are hard black anodized, THEN grey enamel coated to provide the best possible corrosion resistance.