The Stovebolt Site Forums The Shop Area General Truck Talk serial numbers

Are serial numbers the same as vin numbers? My 56 gmc has the plate on the forward pillar drivers side with serial number. I've never seen a vin number anywhere on the truck. I used a link, and it said the truck was made in 61 using the serial number, so that can't be correct, The serial number is 101PY18991. Any information whould be great!

http://www.stovebolt.com/techtips/vin/vinbuster.html

http://www.stovebolt.com/techtips/VIN.htm

With mine a 48 chevy 1/2 ton ... the truck was Vin'ed by the engine number...the door plate is different

Thanks, the first link says it was built in 61, the second link doesn't match up with my serial number??????

Both of those only decode Chevrolet.
Starting around '55, most states went to using the serial number as the VIN, instead of the engine number. Does the number on the title match the serial number on the door pillar?

ive also checked it else where and it comes up as
1961
built in minisota


?????????????????????????????????

what have you really got ?????

I did a bit of research here, from what I can tell (I'm not real well versed in GMC) it's a '55 2nd built at Pontiac. Not sure why it would be registered as a '56, unless it originally cam from a state that registered vehicles by year sold, rather than actual model year. If that's the case, it might have been a late production or leftover '55 stock sold early '56.

I agree with LONGBOX55.

As you might have concluded from the above speculation, the Chevrolet "VIN" buster is of no use busting a GMC serial number.

The Chevrolet truck body/cab ID-codes might have been called different names for different year, but in this case, for Chevrolet trucks, the cab/body code was called (by Chevrolet/GM) a vehicle serial number in 1955-2nd and 1956. GM never called the vehicle serial-number/ID code nor the engine serial-number/ID code a "VIN" code; so, the name of these "VIN" busters adds to confusion by novices and seasoned owners.

As has been posted many times, in most states, until a state-VIN or a national-VIN was defined by law, the "VIN" used for titling/registration could have been the vehicle serial number or the engine serial (as long as it contained some sort of serial number). Some states saw to it that a serial number was stamped into the frame.

As far as GMC goes, the "chassis serial number" was the number on a plate attached to the cab (usually - at least from 1949 through ??) and the difference between a Z-code and Y-code GMC was a difference in model-styles: Z-code was the last of the New Design GMC trucks (1954 and early 1955 GMC trucks) and they were sold into 1955 (into March). The Blue Chip Y-code GMC trucks came out in March 1955 and were given the title/registration year as the year in which they were sold. X-code GMCs came out in 1956.

So, GMC made that 101PY Blue Chip Truck in 1955 (perhaps it was sold/titled/first-registered in 1956) and it most likely has characteristics that are different from those of a 1956 X-series truck. Check if there are any characteristics of your Y-series GMC truck that are unique to 55 or to 56 Blue Chip GMC trucks).

Thanks everyone, great information. Still some questions though. In the run-up to the engine rebuild, my engine guy was checking into parts and discovered that the 248 was only made into 55(correct?). We assumed that the engine could have been a late year build that was put in a 56. The truck has been licened as a 56 since 74, the title is in safe deposit box and I will check on it monday. Also, looking at the codes longbox55 supplied, some things don't match. I have a 248 with a 4 speed and a 11 inch clutch(not 10 as listed). I don't know where the truck was first licened, I can only go back to 74 when a buddy of mine bought it in Kearney Ne. But with everything I've seen here I'm starting to believe that I've got a 55, kind of a shocker after all these years.

1939-1955 for the 248 engine.

As posted above, a late 1955 engine might have been used in truck manufactured in 1955 but first registered/title on 1956.

Can you post the various codes on the head and block (there is a casting-number code and a date code on both the block and on the head)? The engine serial number should be pressed into the ledge in the block just to the rear of where the distributor enters the block (this should show the the engine size).

Here is the location of a date casting code on a GMC-6 block. I'll look for a photo with a more complete set of code-locations (from the oldGMCtrucks site - Rob English annotated a photo with locations).

I will get all the above numbers on Monday, please check back then. This is turning into quite a surprise for me, but it will be great to finnaly find out the true results. I might have to change my handle to "rbs55"

Also remember that factories back then didn't have computer-controlled, bar-coded inventory control. When they ran out of part X, they started using part Y regardless of the year, assuming it would meet form/fit/function requirements. At the beginning and end of year runs, I'm sure that the assemblies got a little blurry.

Hearing of adjacent year items on beginning/end of year runs isn't a surprise.

...and like Tim mentioned, built in year A but sold/titled in year B, etc.


Bill

Does anyone have a picture of the wiring that is routed one the inner fender for a 49 Chevy P/U? I have the wiring and a list of all of the wires and where they are attached. What I dont know is how it looks on the inner fender I know there are terminal blocks on the fenders but not sure where they are bolted. Also where is the fuse block located inside the cab or else where. I bought the truck in pieces and have parts painted and now starting putting it back together

Thanks

Bennie

Well after going throught the linked info I'm quite sure my 56 is a 55. The things that tipped the scales are that in 56 gmc didn't list a 248 as an engine. The other thing that might be the final straw was that in 56 gmc went to all 12 volt systems. If that is correct then my truck is a 55 as it was a 6 volt when I bought it in 75. Can anyone verify the 12 volt only in 56 for gmc? Also, if it is a 55 is the correct way to state it, 55 1/2 or 55 2nd? This is all a major shock after owning the truck for 36 years.

GMC would have called it a 1955 GMC Blue Chip Truck.
Call it anything you like. Technically/Apparently, it was a Y-code GMC Blue Chip Truck first registered in 1956.

Did you, for the heck of it, look for date casting codes on the block/head?

I will get that info on monday when the engine shop opens, also will verify the title and post all the codes on monday, so please check back, this is something that I'm sure doesn't happen much, so bear with my shock.

Bennie,
[IMG]http://img194.imageshack.us/img194/9051/dsc04425vu.th.jpg[/IMG]

Or follow link in signature you should beable to see pictures of what u want there

Ok, here's what I've got. On the block, rear to front, G by it's self, mid block 2324002 then k35 then 3. Above the long number is gmc-7. On the other side aft of the distributer E2483I0432G. On the head 55 then 308 then 1 then 2194819 then an AH. Also a clock face(?) pointer toward 4. On the flywheel 838663-5 GM5 D95. Thanks for any help, even tho I think I've got a 55 instead of a 56.

My guess is (someone may correct me - trust them over me):

K35
K = month = 11
3 = day = 3rd
5 = year = 1955

the gmc/pontiac 347 v8 that has been fitted in my truck also has GM7 on it its supposed to be a 1955 but the trans whitch is with it come,s back as a 1956 car trans ,,,,we think,,,

so you can never be shure what has been swapped / changed over the years

i worked in a bus and truck garage and we were always swapping engine,s and drive lines from one to another,,

Tim, in the link you gave in an earlier post the brocure for the 56 model year has some things that make me scratch my head. 12 volt was standard for the 56 year as was something called "kudu stabilizers" in the engine bay. My truck was 6 volt when I got it and it does have the kudu stabilizers. If you are correct with the engine code dating, that was way late in 55. Did the new models come out after the first of the year back then or did they do it like now with new models coming out in late fall? I was born in 56 which is one of the reasons I've held on to this beast as long as I have so I don't have a clue as to when the model switch happened. Could it be that this was a late run truck that didn't hit a show room till early 56 and still had the "y" code body, but still had several of the 55 parts along with some of the new stuff for the 56 models. And was the 18991 in the serial number the number the truck was off the line? If so how many turcks did gmc produce in a typical year back then?

"Could it be that this was a late run truck that didn't hit a show room till early 56 and still had the "y" code body, but still had several of the 55 parts along with some of the new stuff for the 56 models."

Yes (see below). And the Kudu Stabilizer appears to be a part that GMC made standard in 1956 because of a suspension problem experienced in 1955. Perhaps those stabilizers were an option/add-on in late 1955 (6v used as standard in Blue Chip trucks through 1955)?

"I did a bit of research here, from what I can tell (I'm not real well versed in GMC) it's a '55 2nd built at Pontiac. Not sure why it would be registered as a '56, unless it originally cam from a state that registered vehicles by year sold, rather than actual model year. If that's the case, it might have been a late production or leftover '55 stock sold early '56."

"So, GMC made that 101PY Blue Chip Truck in 1955 (perhaps it was sold/titled/first-registered in 1956)"

"As posted above, a late 1955 engine might have been used in truck manufactured in 1955 but first registered/title on 1956."

"Hearing of adjacent year items on beginning/end of year runs isn't a surprise.

...and like Tim mentioned, built in year A but sold/titled in year B, etc."

"GMC would have called it a 1955 GMC Blue Chip Truck.
Call it anything you like. Technically/Apparently, it was a Y-code GMC Blue Chip Truck first registered in 1956."

I sent you a PM.

"I was born in 56 which is one of the reasons I've held on to this beast as long as I have . . . " Look at it this way - your truck did not get its birth certificate until 1956.

Thanks everyone!!!!!