I had some free time on my hands today, so I put my car on a lift and started decoding. The rearend certainly caught my attention. It makes for some pretty good reading, so here goes.

1966 Chevrolet Chevelle SS396
VIN-138176A139372

VIN decode
138-SS396
17-2 door sport coupe
6-1966
139372-production number

Trim tag
03D
ST66 13817 ATL 9189
TR 763 B M-M
W2LGSR

03D- Body built the 4th week of March 1966
ST66= 1966
13817- SS396 2 Door Sport Coupe
ATL- Body built in Atlanta, GA
9189-Fisher Body Number
TR 763 B- Black Bucket Seat interior
M-M- Solid Aztec Bronze paint
W-Tinted windshield band top only
L-4 speed transmission
G- console
S-rear antenna
R-rear speaker

Block casting number-3855961-1966 396 325hp or 360hp
Stamped on the front deck is T03I4ED6A139372
T-built in Tonawanda, NY
03-built in march of 1966
I4=14-so the 14th day of March
ED- 396-4 325hp-L35 option with 3 or 4 speed transmission
H-Holley carb
6A139372-identifies with the VIN on the car

Transmission
3885010
Built December 18th,1965

Rearend numbers

Date code on chunk - L205-December 20,1965
Housing #-387574N-1966 12 bolt
Axle Ratio code- KM0114 B-KM=4.56 POSI built january 14th B-Buffalo

Heads 3872702 GM1 and same for GM2
GM1 date code is B2_6-Feb. 2nd, 1966
GM2 date code is A176-Jan. 17th 1966

Crank is forged steel with 6223 on it and GMT??? Any ideas? Is that original?

The engine is standard bore and can be built back to standard. How rare is the 4.56 posi? This is as far as I got today.

Any help and thoughts are very much appreciated. Thanks.

With the 4-speed and 4.56 posi, It looks like it was ordered as a drag car. Just wonder why they didn't order the L78?


One source shows 6223 as 366,396,402,427, (68-76)

Well it was a street class car that has never had slicks on it. It was ordered to both race and daily drive. If it was me I wouldve got the 375hp option but everyones different. I do need a distributer, intake and holley carb that matches this date code. That's it, I have all the rest.

Sounds like a nice car. I've got an Aztec 66 SS as well, but mine has the bronze interior.

Thought I had a Holley intake for you, but it's probably too early - dated 3 Jan 1966. PM me if interested.

Where in Mississippi are you? I'm from Pearl River, La, which is a few miles from Picayune, MS.

Scott

Sounds like a "Put together" car to me. December 1965 4.56 rear axle in a fourth week of May 1966 (05D) build date car with a 325HP 396, Dec 18,65 transmission, an engine built 2-1/2 months before the car (with heads dated 1-1/2 and 2 months before the engine build) is also a bit much IMHO. Without a build sheet I'm a little more than skeptical. :noway:

Well, from what Ive read on the internet, the atlanta plant was very far behind around this time period and Ive also read that it isnt uncommon for parts to go back about 90days and still match ie: the engine. They just installed the transmissions and rearends as they got to them. This is a 4.56 posi and there werent many ordered in this combo so there is no telling how long this rearend sat there before it was needed. The rearend is extrememly close to the date code on the transmission as well. I have no reason not to believe the family that I bought the car from. Also, how can you argue with the VIN stamp on the engine? All the part numbers on this car are correct and the guys I bought it from werent knowledgable when it came to cars.

I agree that the dates are not close enough together and what a strange combination; 4.56 rear with a 325HP engine. Is the transmsission a close ratio or a wide ratio? I thought the 325HP engine was only available with the wide ratio, but with a 4.56 rear I would wonder if the close would be used. I'll check my information to see if the 4.56 was available with that combination. So the transmission assembly date is P1218 ? Is there a CON VIN stamped on it that matches the CON VIN on the engine in size and font and general sloppiness? Did you find a casting date on the engine?
Bruce

Im sorry, I admit to being an idiot. I said that my cowl tag showed a build date of 05D. I double checked it and its actually 03D. I feel stupid. Anyways, here is a pic of it and a pic of my engine cast date. engine date is A216. This changes a lot. I am very sorry for any confusion.

03D fits with the 139372 sequence number according to production numbers at Atlanta. And as you say, production quantities stepped up at Atlanta; looks like they doubled production starting some time in February. Production prior to Feb. was 4100 to 4800 units per month, went to 7342 in Feb., then jumped to about 14000 units the following months. The Tonowanda date codes are not usual. The Tonowanda facility usually had only days, not weeks, between casting (heads and blocks) and assembly dates of 325HP engines. But nothing unusual with a T0314 assembly date and the 03D build date of the body. You still need to determine if the transmission has a CON VIN on it (it should if it's original).

The guy I bought it from says that its original, but the original owner couldnt find a VIN on it any where. The car had a different transmission in it when I got it and the owner is shipping the original to me. I have read about them not having a vin stamped on them in 66. I honestly dont know about a con vin on the transmission.

My '65 has a CON VIN on the transmission.

Yes sir, Im sure most had con vins on them from 65+ but Ive read about and heard about quiet a few that didnt get stamped. One of my 70 buick skylark stage 1 cars has all the original drivetrain and the transmission is a correctly coded "BB" transmission (th400) but it is completely blank on the little indented area where the VIN is supposed to be. It basically boils down to how tight of a shift the boys were running back in 1966.

My guess is when you receive the Trans. IT WILL HAVE the VIN on it if it is a ATLANTA Built car.. you will need to let us know.

I will certainly let you know. Is it a big deal if it doesnt have a VIN on it?