SPID vs. VIN vs. Protecto Plate

[hpcgmc]

I don't have the SPID on my GMC, but I've got a "Protect O Plate" -a metal plate that is attached to the original service manual. Can this tell me details about my truck? It had a 327 stock, but when I do a search on auto parts websites, most of them show 1967 C1500 GMC trucks as only coming with 6 cyl engines. I wonder if mine is actually a 3/4 ton, or if it was special ordered with the 327. I assumed that any 3/4 ton would have 8 lug wheels (mine has 6 lug), but I don't know that much about these trucks yet.

Here is what the plate has on it:
top line has the VIN: CE1570DZxxxxA (the "xxxx" is because I'm paranoid to reveal my complete vin)
next line: 327 0000 RXSP44 354 Y
next line: TR 435GA F07881 GMC
next line: the original owners name and the number 40-331

I found a model decoder on GMCPauls, but it only helped me determine C= 2wd, E = v8-gas and 1= 1/2 ton, the rest of the numbers in the vin don't match the GMCPauls numbers.

I'm pretty sure my dad bought it from the original owner in about 1977.

Thanks for any info.