Help identifying differential!
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Joined: Apr 2015
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From: Hialeah Florida
Help identifying differential!
I recently bought a 69 coupe with "numbers matching drivetrain" so far I've identified the block and transmission as being original to the car both have numbers matching the vin, the differential is where I'm confused, the bottom in front of cover has FA 12 28 65 I was able to determine that FA stands for Heavy Duty Posi 3:70-1 gears haven't figured the other numbers. There are other numbers on the differential facing the rear but they appear to be upside down, the top number does not match the vin and the one below that appears to be CM 1, the C could be a G.
Does the differential have a number that matches the vin?
The engine # shows the car to be a 350 manual transmission with a/c.
I will be posting pictures soon, thanks, Tony.
Does the differential have a number that matches the vin?
The engine # shows the car to be a 350 manual transmission with a/c.
I will be posting pictures soon, thanks, Tony.
Team Owner
Joined: Sep 2006
Posts: 31,202
Likes: 4,287
From: Westminster Maryland
Hi Tony,
No, there's nothing on the differential to indicate what car it was installed in originally.
The assembly date stamp on the cover flange and the casting date on the case establish when the differential was produced and thus what time period of production it would be appropriate for.
The FA code appears to indicate a differential made to be used with a 427 engine.
The stamping for 69 differential typically is a number for the shift it was built, the 2 letters (or 3 later in 69 production) for the ratio, the date the unit was produced…month, day, year, and finally a letter for the plant it was built in.
Your numbers seem to indicate a differential from late December 1965 for use in a 427 car.
Regards,
Alan
A photo might help someone decode it more definitively.
No, there's nothing on the differential to indicate what car it was installed in originally.
The assembly date stamp on the cover flange and the casting date on the case establish when the differential was produced and thus what time period of production it would be appropriate for.
The FA code appears to indicate a differential made to be used with a 427 engine.
The stamping for 69 differential typically is a number for the shift it was built, the 2 letters (or 3 later in 69 production) for the ratio, the date the unit was produced…month, day, year, and finally a letter for the plant it was built in.
Your numbers seem to indicate a differential from late December 1965 for use in a 427 car.
Regards,
Alan
A photo might help someone decode it more definitively.
Last edited by Alan 71; May 9, 2015 at 09:38 PM.
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From: Hialeah Florida
Thanks
Thanks Alan, I've been searching and after I made the Thread I took a closer look at the number on the stamp and decided to look at the specs for a 1965 and found similar to what you are saying except I read FA as being a 396, apparently the 12 28 68 is the build code. The differential was serviced 8/22/2000. (At this point I looked for the service receipt)
Alan and everyone reading this, I just found the reason for the numbers being what they are, I have a lot of receipts from the previous owner and one for servicing the rear end, upon closer reading it says (1 Reconditioned Corvette rear centersection).
I guess now I can say I own a piece of a C2.
By the way the car has only been driven approximately 600 miles since all the servicing/repairs were done.
Alan and everyone reading this, I just found the reason for the numbers being what they are, I have a lot of receipts from the previous owner and one for servicing the rear end, upon closer reading it says (1 Reconditioned Corvette rear centersection).
I guess now I can say I own a piece of a C2.
By the way the car has only been driven approximately 600 miles since all the servicing/repairs were done.
Last edited by carretera; May 9, 2015 at 09:54 PM. Reason: Addition
Pro
Joined: Oct 2010
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From: Palm Desert California
Following up on Alan71's response FA= 370.1 HD axle
12=December
28=28th of December
65=? 1965 seems to early but
who knows.
Corvette ID numbers book shows the same but in place of the 65 it shows W for warren plant. If you move up a year to 1970 it shows a G for Chevrolet Gear and Axle . Could the 6 you are seeing actually be a G and if so that still leaves the 5 or S.
Maybe someone else will chime in with more info. Alan71 is correct as usual no vin on the diff.
12=December
28=28th of December
65=? 1965 seems to early but
who knows.
Corvette ID numbers book shows the same but in place of the 65 it shows W for warren plant. If you move up a year to 1970 it shows a G for Chevrolet Gear and Axle . Could the 6 you are seeing actually be a G and if so that still leaves the 5 or S.
Maybe someone else will chime in with more info. Alan71 is correct as usual no vin on the diff.
Team Owner
Joined: Sep 2006
Posts: 31,202
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From: Westminster Maryland
Hi c,
I don't know anything about mid-years but wouldn't a differential built in December of 1965 be used in a 1966 model year car…. and thus be described as being for a 427 engined car.
Regards,
Alan
I don't know anything about mid-years but wouldn't a differential built in December of 1965 be used in a 1966 model year car…. and thus be described as being for a 427 engined car.
Regards,
Alan
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Joined: Apr 2015
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From: Hialeah Florida
Hello!
Hi Alan, what you are saying makes sense by December the new cars are out and as I'm learning now 1966 is when the 427 came out. I'm still looking for information and will try and get a better reading of the casting numbers.
Another question is what differences does this make in the car, I bought it as a numbers matching car and the only number verifiable was the engine which was fine with me, the trans is also original, a few things like intake, carb, ignition, exhaust, etc. are not original. I purchased it for my driving pleasure so the originality is just a conversation piece and the icing on the cake.
Can I still call this a numbers matching car?
Thanks, Tony.
Another question is what differences does this make in the car, I bought it as a numbers matching car and the only number verifiable was the engine which was fine with me, the trans is also original, a few things like intake, carb, ignition, exhaust, etc. are not original. I purchased it for my driving pleasure so the originality is just a conversation piece and the icing on the cake.
Can I still call this a numbers matching car?
Thanks, Tony.
Team Owner
Joined: Sep 2006
Posts: 31,202
Likes: 4,287
From: Westminster Maryland
Hi Tony,
The use of the "numbers matching" description is out of hand and the term has become almost useless.
It means very different things to different people.
For many people it includes just the stamp on the engine block and the stamp on the transmission case.
For others, (me included), it includes a very long list of parts throughout the car.
Can you call it 'numbers matching'? Yes. Only you can decide how much that matters and whether that fact adds to your enjoyment from having the car.
There are MANY people who get far more enjoyment out of their non matching number car than other people with matching number cars. That's a wonderful thing!
Regards,
Alan
Many of the parts on the long list I mentioned are identifiable by their part number, date code, or configuration as being parts that are appropriate for this particular car at the time it was assembled. So some people are very interested in knowing about those things too.
The use of the "numbers matching" description is out of hand and the term has become almost useless.
It means very different things to different people.
For many people it includes just the stamp on the engine block and the stamp on the transmission case.
For others, (me included), it includes a very long list of parts throughout the car.
Can you call it 'numbers matching'? Yes. Only you can decide how much that matters and whether that fact adds to your enjoyment from having the car.
There are MANY people who get far more enjoyment out of their non matching number car than other people with matching number cars. That's a wonderful thing!
Regards,
Alan
Many of the parts on the long list I mentioned are identifiable by their part number, date code, or configuration as being parts that are appropriate for this particular car at the time it was assembled. So some people are very interested in knowing about those things too.
Last edited by Alan 71; May 11, 2015 at 08:15 AM.
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