My 67 or 72, SWB convert build?

[wreckthosecars]

The thread title is because the truck has a 72 cab with 67 front and rear sheet metal. It also has a shorten frame. I thought the frame was a 67 but now I think is a 72 because and the core support mounts on the frame. I'm hoping some one can tell me how to figure out what frame it have.

I'm not planning a show truck. I've built show quality vehicles in the past but this one just gonna be a solid driver.