How to Identify Your GM Alternator


Used on Buick, Cadillac, Chevrolet, GMC, Hummer, Pontiac, SAAB, Saturn History of the GM Alternator

This is just a quick visual identification guide for Delco type alternators.

10DN - 12 Volt, 61 Amp - 1963-1972

delco 10dn series gm alternator

First Alternator used on GM Vehicles to replace old DC Generators. External regulator mounted on the firewall. First used in 1963 on the Corvette.


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Delco 10Si - 12 Volt, 22-72 Amps - 1969-1983

10si series alternator

First internally regulated alternator used by GM. Replaced the externally regulated 10DN. Again, first used on the Corvette. Wasn't into full production until about 1962.


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Delco 12Si - 12 Volt, 78-94 Amps - 1983-1987

delco 12si series unit


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15Si - 12 Volt, 85-105 Amps - 1982-1984

 delco 15si alternator


17Si - 12 Volt, 120 Amps - 1986-1990

17si unit 


21Si/22Si - 12 Volt, 70-160 Amps -

21si 22si unit

The 21Si and 22Si are near identical cosmetically. Internal differences are...


27si type 100 unit

27Si / Type 100 - 12 Volt, 100 Amp - 1973-1985

27si type 100 unit


delco cs130

CS130 - 12 Volt, 100-105 Amps - 1986-1997

cs130 series unit

Upgraded from the 10Si and 12Si.


cs130 unit

CS130D - 12 Volt, 100-110 Amps - 1994-Present

cs130d series unit

A retooling of the flaws found in the original CS130.


cs130d

CS144 Early - 12 Volt, 120-124 Amps - 1986-1995

cs144 early

Upgrade from the 15Si and 17Si. Same Bolt Pattern.


cs144 late

CS144 Late - 12 Volt, 140-145 Amps - 1991-Present

cs144 late

Used an upgraded bearing and battery post assembly