Question: What document identifies the Numbers in a Numbers Match car?

[rojo_atlanta]

I have an '81. First, I've visited several forums and cannot seem to determine one thing, probably because it's based on opinion: Which specific stamps (engine block, transmission, frame, etc.) must match, to qualify as a Numbers Match car? Somewhere is there a simple list of these?

Secondly, if I'm going to match the numbers for my car, who sells the list of numbers I'm matching to, GM dealers or the NCM? (I know the NCM sells Build Sheets, but I don' think that's what I need.)

Thanks for your help!!

 

[hotmtrsports]

I've always understood "Numbers Matching" to mean matching to the serial number of that car and the production dates of the original parts in that same car when it was manufactored:

Engine and transmissions should all reflect the serial number of that car. The rear axle should have the codes to signify the production date and be very close to the production date (before) your car was born and also have a code that shows the year and axle ratio again matching what should be in your car.

Sample: numbers on the alternator should have a number stamped on it and the date it was manufactored. It would not make sense that the alternator was manufactored Jan of 1982, if you have a 1981.

So you can't "buy" a list, your car's serial number and production date are what everything goes by.

I've looked at cars the sellers state matching numbers only to find out the engine is matching, but the transmission is wrong, the alternator is wrong, the exhaust has been changed to headers, etc etc. That to me is NOT a numbers matching car.

My take on matching numbers is more serious than others.

If you want to check your car against what the numbers should be, you can get started by buying the Corvette Black Book and a repair manual.

According to the Chilton's Repair Manual from any parts store:

Your 81 should have (if it's non-California and it has automatic transmission):

Engine code: ZDD with the car's serial number next to it stamped on the block.
Alternator number should have either 1103103, 1103091, 1101075

As you can tell, you can go nuts making sure you have numbers matching and that's why these cars demand more money. The closer that car is to matching what should have been on the car, the more valuable it is. It's sssooo easy to change the alternator to a rebuilt only to give up the original one as a core, etc, etc. To me buying replacement mufflers that have the original shape and original GM part number stamped on it would qualify as a numbers matching part.

Some people may say numbers matching doesn't mean a whole lot, I say if you want to strive for it, go for it. It's a challenge and I believe when it's time to sell, it WILL make a difference even if it's just to show the respect of the cars history. It DOES make a difference to me as a buyer.

I got a bit wordy but hope this helped.

Chuck M

 

[Vettehead Mikey]

You can't find an official list of what constitutes 'numbers matching' because none exists, nor is there a person or organization that grants a car 'numbers matching' status. If somebody says NCRS or Bloomington Gold, give them a smack from me, it's false.

Ask 10 people what it means to them and you'll probably get 12 different answers.

Here's a good point to ponder- does 'numbers matching' also mean the actual, original part that was installed on the assembly line, or would any piece with similar numbers also qualify? How about restamped engines (very common on rare high dollar cars) - are they 'numbers matching' too?

It's a hackneyed, meaningless term in today's hobby, most serious guys don't use it.

 

[6880 Mike]

At the assembly plant, a VIN derivative (not the complete VIN, but shorthand with the consecutive unit number) was stamped on the frame in two places, on the transmission, and on the pad on the engine block at the front of the right head. Most people are happy if the VIN derivatives stamped on the engine and tranny match the vehicle's VIN. Those two show the engine and transmission are original to the car

The trim tag on the driver door post will tell you the date your car passed the station on the assembly line where the tag was attached. For St. Louis cars, this will be a code for month and day. For Bowling Green cars, the code will be be for month and week of the month and not show a specific day.

All of the parts on your car were at the assembly plant before assembly of your car began. Everything (literally) with a date code on your car must be dated prior to the time/build code of your Corvette. If you want to match dates and numbers, begin with the time/build date and work your way backwards in time.

Do you have any reason to believe your engine and transmission are not original?

 

[rojo_atlanta]

Thanks Mikey. That's a simple, straight-forward answer

You can't find an official list of what constitutes 'numbers matching' because none exists, nor is there a person or organization that grants a car 'numbers matching' status. If somebody says NCRS or Bloomington Gold, give them a smack from me, it's false.

Ask 10 people what it means to them and you'll probably get 12 different answers.

Here's a good point to ponder- does 'numbers matching' also mean the actual, original part that was installed on the assembly line, or would any piece with similar numbers also qualify? How about restamped engines (very common on rare high dollar cars) - are they 'numbers matching' too?

It's a hackneyed, meaningless term in today's hobby, most serious guys don't use it.

 

[rojo_atlanta]

No, I have no reason to believe mine do not match. They probably do. I just wanted to figure out what is worth checking. Thanks Mike!

At the assembly plant, a VIN derivative (not the complete VIN, but shorthand with the consecutive unit number) was stamped on the frame in two places, on the transmission, and on the pad on the engine block at the front of the right head. Most people are happy if the VIN derivatives stamped on the engine and tranny match the vehicle's VIN. Those two show the engine and transmission are original to the car

The trim tag on the driver door post will tell you the date your car passed the station on the assembly line where the tag was attached. For St. Louis cars, this will be a code for month and day. For Bowling Green cars, the code will be be for month and week of the month and not show a specific day.

All of the parts on your car were at the assembly plant before assembly of your car began. Everything (literally) with a date code on your car must be dated prior to the time/build code of your Corvette. If you want to match dates and numbers, begin with the time/build date and work your way backwards in time.

Do you have any reason to believe your engine and transmission are not original?

 

[rojo_atlanta]

That was very helpful. Thanks hotmtrsports!!

I've always understood "Numbers Matching" to mean matching to the serial number of that car and the production dates of the original parts in that same car when it was manufactored:

Engine and transmissions should all reflect the serial number of that car. The rear axle should have the codes to signify the production date and be very close to the production date (before) your car was born and also have a code that shows the year and axle ratio again matching what should be in your car.

Sample: numbers on the alternator should have a number stamped on it and the date it was manufactored. It would not make sense that the alternator was manufactored Jan of 1982, if you have a 1981.

So you can't "buy" a list, your car's serial number and production date are what everything goes by.

I've looked at cars the sellers state matching numbers only to find out the engine is matching, but the transmission is wrong, the alternator is wrong, the exhaust has been changed to headers, etc etc. That to me is NOT a numbers matching car.

My take on matching numbers is more serious than others.

If you want to check your car against what the numbers should be, you can get started by buying the Corvette Black Book and a repair manual.

According to the Chilton's Repair Manual from any parts store:

Your 81 should have (if it's non-California and it has automatic transmission):

Engine code: ZDD with the car's serial number next to it stamped on the block.
Alternator number should have either 1103103, 1103091, 1101075

As you can tell, you can go nuts making sure you have numbers matching and that's why these cars demand more money. The closer that car is to matching what should have been on the car, the more valuable it is. It's sssooo easy to change the alternator to a rebuilt only to give up the original one as a core, etc, etc. To me buying replacement mufflers that have the original shape and original GM part number stamped on it would qualify as a numbers matching part.

Some people may say numbers matching doesn't mean a whole lot, I say if you want to strive for it, go for it. It's a challenge and I believe when it's time to sell, it WILL make a difference even if it's just to show the respect of the cars history. It DOES make a difference to me as a buyer.

I got a bit wordy but hope this helped.

Chuck M

 

[Vettehead Mikey]

Thanks Mikey. That's a simple, straight-forward answer

It used be that the phrase always meant 'original engine from the factory' but over the decades it's been thrashed into umpteen different meanings. I saw one recently with a small block car converted into a big block clone and offered with a 'replacement original numbers matching engine':confused

My favourite definition was the buyer's 'offered $ number' matches the seller's 'willing to accept $ number' :L