1970 LT-1 alternator ID

[Dave C]

I recently had to do some alternator work on my 1970 LT-1 and I am trying to determine if it is the original one. The alternator number is 1100884 and it is stamped 61 amps which I believe is correct. The date code is OG13 which I believe is July 13, 1970. The date of manufacture of my car according to the paint code tag, which is G21, is February 21, 1970. If all of this is correct, then the alternator was built after my car and must have replaced the original shortly after the car was bought and is therefore not the correct one. Is it possible that I am missing something and this is actually the correct alternator? Thanks for any help!

Dave #41316

[Terry M.]

Re: 1970 LT-1 alternator ID

Dave,
1970 Corvette production started in January, so for your body build date (from the trim tag) G21 = July 21. Be happy! Your alternator date is right in line with what one would expect.

[Joe L.]

Re: 1970 LT-1 alternator ID

Dave-----

As Terry says, it's EXTREMELY likely that the alternator is original to the car.

Also, this, particular, alternator is quite rare, both with respect to case configuration as well as part number. It should have the "6 thin rib" configuration for the drive end case half, with the cooling opening between the ribs extending all the way to the case perimeter. This style case half is unique to 1969 and 1970 SI series (i.e. internal regulator) alternators.

The split ring (i.e. rear) case half is unique to 1970. It should have the "7 fin" heat sink cast in the back of the cover. This part of the configuration is unique to both 1969 and 1970 SI series alternator split ring case halves. The 1970 case half has a raised boss for the alternator grounding lug, whereas the 1969 has a nearly flush boss. Also, the 1970 case half has the raised Delco Remy script like 1969, but there is a very slightly raised rectangular casting mark below the script. 1969 does not have this feature. So, the COMBINATION of features ( "7 fin", raised grounding lug boss, and rectangular casting mark) are features that identify the 1970 Corvette split ring case half.

There were several style case halves that followed for both drive and split ring ends. These are functionally interchangeable with the 69-70 parts, but they're not "correct" for those years.