How does a pre-1972 SPID designate GMC or Chevy? SPID example for GMC?

[71CHEVYSHORTBED402]

This GMC decoder for a 70-71 GMC shows just five digits for a serial number.

The 67-72 decoder shows six digits. Is that the only indicator on a SPID that distinguishes a GMC from a Chevy in 1970-71? Edit, nope: The VINS differ in a number of ways.

Thus real life example KE141Z654372 must be a Chevy? It's a SWB (model KE10734), I don't suppose many Chevy SWB K10 were built. FWW, the truck's build date is on the same day as my SWB C10, separated by <200 trucks, both serial and sequence numbers.

K = 4WD
E = V8
1 = 1/2 ton
4 = Pickup
1 = 1971
Z = Fremont
6 serial numbers

[71CHEVYSHORTBED402]

After studying the decoders a bit more, the difference GMC and Chevy is more than just 5 VS 6 serial numbers. For starts, a 1971 GMC has a 13 character VIN while a Chevy has 12 characters.

Real Life Examples:
CE141Z654XXX
C 2WD
E V8
1 1/2 TON
4 PICK-UP
1 1971
Z FREEMONT
6 DIGITS SERIAL #

KE141Z654XXX
K 4WD
E V8
1 1/2 TON
4 PICK-UP
1 1971
Z FREEMONT
6 DIGITS SERIAL #

If the K truck was a 1971 GMC and all else equal, then the VIN would read:
KE104?Z1XXXXX
K 4WD
E V8
1 1/2 TON
04 FENDER SIDE
SPACE FOR DESIGNATION LIKE WHAT?
Z FREEMONT
1 1971
5 DIGITS SERIAL NUMBER

[Keith Seymore]

I agree; it doesn't seem to be captured in the VIN until '72.

For a squarebody it's in the model code, ie:

TK10903 = GMC, 4wd, 1/2 ton, lwb, reg cab pickup

CC20943 = Chevrolet, 2wd, 3/4 ton, lwb, crew cab pickup.

That does not seem to be the case for 67-71.



K

[71CHEVYSHORTBED402]

Originally Posted by Keith Seymore

I agree; it doesn't seem to be captured in the VIN until '72.

For a squarebody it's in the model code, ie:

TK10903 = GMC, 4wd, 1/2 ton, lwb, reg cab pickup

CC20943 = Chevrolet, 2wd, 3/4 ton, lwb, crew cab pickup.

That does not seem to be the case for 67-71.



K

I think I figured it out Keith, post two. The "designations" in the VINs vs are about half different. They made things more difficult than they had to be, pre-1972. Perhaps whomever came up with the idea had previously worked for the government, or they had a future in it

FWW, here's a 1972 GMC decoder to add, next to a 1972 Chevy. Both follow the same logic.

[402Bowtie]

67 gmc = "C" in the vin
68 gmc = "B"
69 gmc = "A"
70 gmc = "Z"
In 71, it went factory code followed by "1"...S1, Z1, etc
In 72, it went "2," plant code digit, "5"... 2S5, 2Z5 etc. Only gmc trucks had a "5" after plant code in 72.

[Keith Seymore]

Originally Posted by 402Bowtie

67 gmc = "C" in the vin
68 gmc = "B"
69 gmc = "A"
70 gmc = "Z"

Forgive me, but I am not seeing that in the VIN decoders.

https://67-72chevytrucks.com/vboard/...d.php?t=570059

[EDIT - I see it now! Chevy and GMC denoted the model years in a different fashion!]

[EDIT - That makes the following kind of moot, but I'll leave it in so my work is not wasted]

Originally Posted by 402Bowtie

In 71, it went factory code followed by "1"...S1, Z1, etc
In 72, it went "2," plant code digit, "5"... 2S5, 2Z5 etc. Only gmc trucks had a "5" after plant code in 72.

For conversation sake - I normally think of it as the plant code, followed by the sequential portion of the VIN (just the way my mind breaks it up).

I agree with your assessment for '72. It would be model year ("2"), followed by plant code, followed by sequential portion of the VIN (the serial number), where:

Chevrolet starts with 100001
GMC starts with 500001

Taking what you have pointed out and saying it differently, my summary would be:

67 GMC: (plant/year/serial) XC 1001
67 Chevy: (year/plant/serial) 7X 100001

68 GMC: (plant/year/serial) XB 10001
68 Chevy: (year/plant/serial) 8X 100001

69 GMC: (plant/year/serial) XA 10001
69 Chevy: (year/plant/serial) 9X 100001

70 GMC: (plant/year/serial) XZ 50001
70 Chevy: (year/plant/serial) 0X 100001

71 GMC: (plant/year/serial) X1 10001
71 Chevy: (year/plant/serial) 1X 100001

72 GMC: (year/plant/serial) 2X 500001
72 Chevy: (year/plant/serial) 2X 100001

That - is ridiculously nuanced.

K

[Keith Seymore]

So - to answer the original question (that is, "How does a pre-1972 SPID designate GMC or Chevy?") the answer is it does, but it's clunky.

The '72 VIN format would be the first usage of the "modern" format, carried over into the squarebody era and (basically) still in use today.

Additionally, the actual options appear on the SPID for a square, specifically:

X88 = Chevrolet Nameplate Conversion
Z88 = GMC Nameplate Conversion

K

[402Bowtie]

Originally Posted by Keith Seymore

Forgive me, but I am not seeing that in the VIN decoders.

Taking what you have pointed out and saying it differently, my summary would be:

67 GMC: (plant/year/serial) XC 1001
67 Chevy: (year/plant/serial) 7X 100001

68 GMC: (plant/year/serial) XB 10001
68 Chevy: (year/plant/serial) 8X 100001

69 GMC: (plant/year/serial) XA 10001
69 Chevy: (year/plant/serial) 9X 100001

70 GMC: (plant/year/serial) XZ 50001
70 Chevy: (year/plant/serial) 0X 100001

71 GMC: (plant/year/serial) X1 10001
71 Chevy: (year/plant/serial) 1X 100001

72 GMC: (year/plant/serial) 2X 500001
72 Chevy: (year/plant/serial) 2X 100001

That - is ridiculously nuanced.

K

Almost. What you have for 69 chevy and 71 chevy aren't quite correct.
69 chevy: 9X8
71 chevy: 1X6 or 1F8

The patterns are easier to see in the build date project thread (posts 63-65).

[Keith Seymore]

Originally Posted by 402Bowtie

Almost. What you have for 69 chevy and 71 chevy aren't quite correct.
69 chevy: 9X8
71 chevy: 1X6 or 1F8

The patterns are easier to see in the build date project thread (posts 63-65).

I see it now.

So the generic decoder is not correct for 1969 Chevy (VINs start with 800001) or 1971 Chevy (VINs start with 600001 or 800001).

Thank you -

K

Udated:

67 GMC: (plant/year/serial) XC 1001
67 Chevy: (year/plant/serial) 7X 100001

68 GMC: (plant/year/serial) XB 10001
68 Chevy: (year/plant/serial) 8X 100001

69 GMC: (plant/year/serial) XA 10001
69 Chevy: (year/plant/serial) 9X 800001

70 GMC: (plant/year/serial) XZ 50001
70 Chevy: (year/plant/serial) 0X 100001

71 GMC: (plant/year/serial) X1 10001
71 Chevy: (year/plant/serial) 1X 600001 or 1F 800001

72 GMC: (year/plant/serial) 2X 500001
72 Chevy: (year/plant/serial) 2X 100001

[dagnabbitt]

You guys seem to be discussing 70-71, but it just to be annoying: between 67-69 Canadian GMCs and American GMCs didn't have the same VIN convention.

The Oshawa plant put a "9" in the second field/space to denote GMC. My 67 "920" is K9247... etc.

[Keith Seymore]

Dagnabbit Dagnabbitt!

I gotta stop now before my head assplodes.

K