Particle board is what i've seen most of the original cabs were made out of, usually with a mix of plywood for stuff like the back door..
MDF was like unheard of back in the early 80's, It's become popular recently due to home improvement shows like Trading Spaces..lol...it's basically cardboard, while particle board is tiny pieces of wood and sawdust glued together..not to be confused with OSB which is large chips of wood glued together (which would be horrible for a cab).
Partical board holds a screw quite well, but the edges dont usually sand very smooth which is why t-mold is used...mdf gives nice paintable edges but for strength and screw holding it's terrible
Both suck if they get wet...plywood is better for a damp environment.