Protect-O-Plate Decode 1967 K15
 

I found and scanned the Protect-O-Plate from my 1967 K15 today and I'm trying to figure out what all the numbers mean.
I know the VIN is the first two numbers and "305E" is the engine. I think 464657 is the serial number from the engine.
"RXSTD" would seem to refer to the rear axle as being a standard and "3.54" would be the rear ratio, right?
"ID56885" should match the rear axle serial #.
"TRSM318" refers to the transmission type, which I am pretty sure is an SM420 (manual 4-speed with 7.05:1 low first gear). What does the "P" after "GMC" mean? It doesn't seem to line up with anything.

Any ideas? Have I gotten anything wrong in the list above?

Re: Protect-O-Plate Decode 1967 K15
 

The SM318 is a three speed transmission. If you've got an NP420 four speed now, a previous owner must have replaced the three speed. You can find more VIN info at http://6066gmcguy.com/VinNumber.html and http://6066gmcguy.com/GMC-vin-list-6769.html

Re: Protect-O-Plate Decode 1967 K15
 

Greetings, Nashville!

TRSM318 indicates that the truck was equipped with a three speed transmission. If the plate had read TRSM420, that would be the code for the four speed transmission.

Re: Protect-O-Plate Decode 1967 K15
 

That's exactly what I thought, but that's not consistent with everything I know about the truck. The first and only owner prior to me was my employer. The truck was bought in 1967 as a work truck and sat unused for the past 20+ years until I resurrected it this year. I have the original bill of sale with all the info from a long-defunct dealership here in Nashville. It lists the truck with "305E Motor, 4 speed trans, 4 Wheel Drive, etc" so the SM420 4-speed would appear to have been the transmission that GMC shipped it with, unless the dealer swapped transmissions prior to sale. That seems unlikely, but not beyond possibility. Perhaps the Protect-O-Plate is in error?

I know the truck cost $2,938.65 when new and was purchased on 13 Oct 1967, presumably as the last-of-stock on '67 model year, since the '68 models would have been out at that point.

Thanks for all the thoughts.

Re: Protect-O-Plate Decode 1967 K15
 

In my opinion, it's unlikely the factory mis-labeled the transmission. More likely is that the original owner found the new truck on the dealer's lot and asked for the trans swap. Back then it was common for dealers to do things like that. For example, before he took delivery, my Dad had the dealer swap the 305 for a 351 and install an auxiliary two speed transmission in my one ton Suburban.