One thread for everything to do with the VIN decoder:
Chevy & GMC VIN Decoder - FullSizeChevy.com
If something didn’t work, tell me what you did and what happened — typed or photo, phone or computer, and which browser if you know it. “I uploaded a photo of my door jamb and it just sat there” is a perfectly good bug report. If it decoded but got something wrong, post what the tool said, what the truck actually is, and what it should have said. Wrong answers matter more than missing ones.
Squarebody is where it’s thinnest. 1981-up runs against the federal VIN standard, but 1973-80 predates that standard, so that decoding layer is ours to sift through and it has gaps. We’re still working on filling those gaps out, but if you’re running a 73-80, you’re the most likely to find a bug and the most useful person to hear from.
Hope it helps!
Todd