My guesses (I have not seen factory documentation for Chevrolet truck colors for some of these parts):

transmission - raw cast (changing to rust color, eventually)
clutch housing - raw cast (changing to rust color, eventually) - engine color

"Cast Blast" is sometimes used to keep the "new look" on those parts.

GMC painted those parts non-gloss black

Here are 1950 Chevrolet truck color names - scroll down the three pages

Here are color names and paint codes.

Hopefully, someone will past information/links for modern equivalent colors for the interior colors.

Last edited by tclederman; 10/19/2014 9:24 PM. Reason: corrected after Denny posted info