Parts & Illustration Catalog
 

I think I've found the right manual I'm guessing the "P" just denotes parts catalog. It doesn't refer to some manufacturing code does it?

This is it.

Yeah, I would assume it just stands for 'parts'. I do not know of a light truck series designated with that letter.

I have the parts list & illustrations manual for the earlier light trucks. I do not remember if mine have a P or I on either of them though. I would have to take a look once I get home.