Not positive but didn't Cokes originate with the .44 Magnum (pre-29). Don't think I have seen Cokes on any other guns other than .44 and .41 Magnums... All the other N-frames had diamond walnut. Think they were phased out around 1966/67...
The pros like Doc44 over on the S&W forums would have a more accurate answer...
Is life so dear, or peace so sweet, as to be purchased at the price of chains and slavery? Forbid it Almighty God! I know not what course others may take, but as for me, give me liberty of give me death! P. Henry