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.

Parts Page

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.

Parts Page

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

delco 12si series unit

Parts Page

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