The Chiefs Special came with a blue or nickel finish from the first year of manufacture, and yours left the factory with a nickel finish. The N stamps on the back of the cylinder and the lower side of the grip frame confirm that!
The other stamps you asked about are assembler's, fitter's, or inspector's marks. The matching five digit numbers on the yoke and lower side of the grip frame are assembly numbers and serve now to confirm those are the gun's original parts.