New member in Nebraska...with a question

[big steve-o]

Hello, all. I just joined up, and I'm a big fan of squarebody trucks. I learned to drive at age 12 in my grandfather's 1977 Custom Deluxe. Crank windows, no AC, manual steering, manual brakes, single cab, LWB, your basic strip job. About 9 years later, he gave me the truck with less than 50k original miles on the 250ci six. I joined the service the same year, and drove the truck from Virginia to Texas and back to North Carolina. Unfortunately, a few years later I was working on a drag Mustang, and sold the truck to buy a racing transmission. That was a bit over 10 years ago, and remains one of the most regretted decisions I have made. I'm finally jumping back into the ring and buying a 1980 Custom Deluxe...........Which brigs me to my question:
I looked over the "VIN decoder" from this site, and the VIN on this truck doesn't seem to jive. It's 13 digit, like it should be, but the VIN starts with CCG. Which should indicate Chevrolet, 2wd, but the engine indicator should be D,L,R, or T. And it has a 305 in it. I would have guessed swap, but the emissions sticker matches, it's all the same factory paint, and that VIN!! I haven't found any info for CCG as the first 3 in a 1980 VIN. Any insight? Sorry for the long winded first post.