Should be a TH400.

I wouldn't crawl under to take a specific look - it's probably original. Next time you're under there for something else and in the vicinity, take a look then.

I think you probably have an original CPH block in your 71. Someone goofed.

No real harm done and it makes an interesting topic of conversation.

 

 

Interesting. I'd crawl under there right away and take a look, because without that, everything else is speculation. That's just me.

 

So I did some digging last night and was able to find the tank sticker which told me it is a 454 LS-5. The transmission line was blank, and at the bottom under "comfort and con", it listed standard transmission, which would be a M-20 Muncie correct? Here is the confusing part. The frame has a z bar support welded to the frame as well as an automatic trans cross-member bolted in. The automatic frames have the nuts for the cross member bolts welded to the inside of the frame before they weld the 2 halves together so I am not sure how they would convert it from a manual to an automatic. There is no obvious cutting and welding on the bottom where it could have been converted. Plus I was able to find the VIN on the rear portion of the frame and that matches the motor and car VIN. Any help or ideas? I'm very puzzled by this.

 

From personal experience working for GM in the early 80's, I can attest to factory goof ups.
I worked at the Oldsmobile division dealership level parts dept as a parts counterman.
We had a batch of Oldsmobiles come through with a Y code(Pontiac)
350cid engine installed.
Threw everybody for a loop when ordering engine/electronics parts till we figured it out.
I don't think we ever revealled it to any of the customers.
Some how they used up/mixed up these engines on the Olds assy line?
So, yes it happened in the 80's, I'm sure it happened in the 60's/70's too.
Thee liquid lunch was still alive and well practiced in the 80's so I can only imagine what it was like in the 70's
The tank sticker is the build sheet GM followed.
It went from dealer order to build to delivery.
Your Towanda sequence # looks right as these were stamped w/ the heads off from what I've come to learn.
When you see the Towanda date stamp lined up with the vin stamp I get the restamp feeling sensors going off in my head.
And yes as stated, these two stamps are supposed to be different sizes. I see nothingg wrong either with the pad.
Kinda makes it like the coin that has the date stamped upside down.
Makes for a great conversation piece, oh and don't forget to enjoy it whille yor at it
Marshal

 

The M20 was the standard transmission; it would not be listed on the tank sticker. The TH400 in your car was an option. If it was original, it would be on the tank sticker. Post a pic of your tank sticker.

While you were under there, did you find the VIN derivitive stamp on the tranny?

It's beginning to look like your car may have been a factory four speed car and has been converted to automatic. That would explain the CPH suffix.

 

Can't imagine converting a car to a bolted crossmember.

 

Its all very strange. If they changed it out they went through a lot of trouble changing all the console hardware over to the correct style trim plate with original engine data tag. If I pull one of the bolts out of the bottom cross member and there is a nut on the other side then I will really be confused.

At the bottom of the tank sticker there is a code and a description for a standard transmission. I have seen a few other tank stickers coded this way.

The tank sticker will be tough to read via a photo.
I will provide all the codes on the sticker later tonight.

Also is there any good reference of the dealer codes and Zones from these tank stickers? NCRS has some info but its very little.

 

Installing an engine and auto trans together in a car with a welded crossmember can be done. But, you can't remove the auto tranny by itself when you get done (unless you cut the crossmember).

 

I know:
Block VIN matches windshield frame VIN which matches frame VIN,which all corresponds with door trim tag which corresponds with tank sticker.

Only issue is an auto transmission with a bolted cross-member.

From what I can see where the VIN derivative should be on the trans there are a few numbers that look like this 00300. These are in the larger font similar to the Tonawanda stamping. Trans is the correct TH400, but unsure of Date on trans tag.

 

You may not find reliable information on dealer codes since dealers could change from year to year. Zone code information would probably be more reliable.

Have you checked on a shipping data report for your car through the NCRS?

 

This car is in the C3 registry from just a couple of months ago, looks like you purchased it as a project and a basket case, pretty much disassembled.

looking at the registry pics, it is hard to make a statement that the engine has never been out.

the approximate birthday of April 12th makes that engine block 75 days or so old prior to the car build. 75 days is ok by NCRS judging being typical of factory but is approaching the extreme end of what would not be questionable.

also the block sitting at the factory for nearly a month prior to being built is questionable.

I also see a tad of old paint on that stamp pad pic. Stamp pads were not painted at the
factory. make me suspect that the engine has been out. when an engine has been out.. anything can happen.

add all the date line up issues and painting of the pad together with the wrong broadcast code and I would not be convinced that this is the original engine. perhaps restamped by someone with the correct stamps but the wrong knowledge.

if I was buying a original engine car, the dates would have to line up closer and the stamp would have to be correct. This is just a car with several excuses, or NOM.

 

I went to great lengths to install a 5spd in a Camaro just for ease of installation, on that car none of the original aspects mattered! As a previous post said if the motor came out ... interesting to find out the answer.

 

I do not disagree, but we have to keep in mind 71 was a strike year. No cars were produced from about mid-September 70 until very nearly Thanksgiving. Production did not ramp back up to "normal" until December. By that time, orders were likely to have been backed up for nearly three months.

Normally, a block cast at the end of January, not assembled until late in February, and not installed in a Corvette until the middle of April would raise eyebrows. In this case, the date span may mean nothing more than St. Louis scheduling the back log of builds as best they could.

Ryan: can you read the date in the Date Received block at the top of your tank sticker?

 

Joewill - You are right it is in the C3 Vette registry. It was in a corvette resto shop that went out of business back in the mid 90's and sitting there till recently, in the condition its in now.