VIN decode help, confused?

[chillware]

Hey Guys,

I've been looking at my VIN again, since I've just looked at the cab again for the first time in about a year. So the VIN on the cab doesn't match the VIN on the frame at all, from what I've read it should at least partially match.

The VIN on the cab is C144 6Z155366 (see pic below) which I think I've properly decoded to 2WD 1/2 ton stepside shortbed pickup 1966 Fremont. All fine a dandy, only this isn't a step side pickup. Which I've been suspecting that the cab didn't belong to this frame because of weird things I've run in to on the frame along my build.

I *think* the frame is actually a '64 based on the 12 bolt rear end that's in it that had the old 17 spline axles and the '64 style panhard bar mount.

What I'm having trouble with is the VIN on the frame, it is H142946. It is clearly stamped and I'm positive that's exactly (and all) it says.. I cant figure out what the H is or what year it is? From what I've read I know it should only be the plant, year and serial number. But I can't find a plant code of H any place..

Any ideas?

Thanks again!!