I have my 1971 LT-1 up for sale. I have an interested buyer. He asked about a code located behind the power brake booster. It is supposed to be below the emmissions sticker with the timing and idle speed specs.
I was told it was painted by hand. It should have 2 letters no numbers. I looked and saw what appears to be a C and a 1 . The buyer is telling me it should tell what engine and transmission the car originally was built with. I already have confirmed that the engine and the transmission have the VIN numbers. He is still asking about the code for the firewall.
I am guessing that at one time it read GZ and over time it looks more like a C and a 1. The engine has CGZ on it. I am guessing this was for assembly line purposes. I was told the C indicates car rather than an engine for a Truck. G should be LT-1 350 330HP and the Z would mean the M-21 close ratio transmission . So if this is correct would the firewall code read GZ back when it was built ? Thanks , Joe

 

He's talking about the Emission Decal code which should be an AX for your vehicle if it's a 71 LT-1.

 

Thanks , I will check the Emmissions sticker for the AX. I am sure the emmissions sticker is the correct one for this car. The car only has 35,400 miles on it and the sticker is in great shape.
The guy was telling me his friend has a 1969 427 and it has 2 letters painted by hand below the sticker . He said they were put on with what almost looks like "white out ", in that spot is where I found what looked like a C 1 . I have seen restored Camaros Novas and Chevelles with 2 letters painted on the firewall as well. I have seen the code PJ .
The prospective buyer wants to make damn sure that my car is not cloned. I am just trying to cooperate with the guy. Thanks for writing.

 

Sounds like the buyer doesn't know half as much he thinks he does and is running you in circles.

There are occasionally markings in white crayon in the location you mention (or in other places on the underbody) but I'm not aware of engine type being one of them. Usually the marking denote options like power steering, power brakes, air con, h/d suspension or the like.

If he's not satisfied with the engine and transmission stamp pads, tell him to pound sand.

 

Z in CGZ does not mean M21. CGZ was just the LT-1 engine code. May have come with M20 or 21. CGZ should have been written upside down in crayon on the block and may be visable under the exhaust manifolds, but I've never seen or heard of anything writen in the engine area that would indicate the engine option.

 

Thanks for the input guys , I appreciate people taking the time to write. I was under the impression the CGZ meant M-21 close ratio because the ZR-1 equipped with an LT -1 has CGV and there would be an M-22 behind that. I figured the last letter designated the trans V vs a Z .
The guy did come and look at the car . We spent close to 3 hours together. He was bugged about a code on the carb. I know the carb is the original one . There were 2 sets of numbers on the carb. One set was correct according to him and another set did not match what he had written down. The owner I bought if from told me about someone that he had re do the original carb. The guy is from Lyndhurst NJ and I have heard the guy has a good reputation.
To tell you the truth the main reason I want out of this particular car is because it is a numbers match car. I would prefer to sell it to someone that will take it to the next level . I don' like the 4.11 gears. If I change the rear I would prefer a lower first gear, instead of the 2.20 first. I really don't want to go taking this one all apart. There are a lot of good deals out there right now and I think I would rather have one that is not so much of a time capsule. Thanks , Joe