« Reply #3 on: February 05, 2015, 10:53:27 am »
Looks like a 27SI. Your pictures do not show the mounting ears from the side, but it looks to have 2 ears on the bottom mount. The back one having a bushing in it. The inside distance between the ears should be 2.60" and be 0.39" Diameter.
27SI has a high amp output at idle. It is recommended for passenger car and light trucks when high output at idle is necessary. There is a 100 A and an 80 A version. The 80 A version has a special R-terminal for use with electric tachs and tach hour meters, etc.
The only Original to Service 27SI-100 part number that I could find is 1105500 (AC Delco Reman. #10459234 and AC Delco Catalog #321-744
There are 2 Original to Service 27SI-80 part numbers that I could find: 1101058 and 1101061 (Delco Remy Reman. #'s: 19020504 and 19020504, respectively)
« Last Edit: February 05, 2015, 10:59:24 am by ehjorten »

Logged
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6