Aloha, I've scoured my '59 restoration package and my personnal paint chip books, (dulux & duco)I can't find it either. This also further complicates things, as per "Dupont 1960 CHEVROLET COLOR BULLETIN No. 32 (sheet 5)
------------------------------------------------
RPO combination letter designations are:
A = Over-all (solid color)
TWO-TONE COMBINATIONS
B = 1405-3605 Models
C = 1406-1416 Models
D = All Cabs, except Fleetside
J = Fleetside
No "K"
--------------------------------------------------
AND, I just turned the page to the 1961 chevy truck colors and theres a 729 (L), anyway the name of that color is "Flaxen Yellow" which is a color for "59, but is #718A!! Kinda confusing huh?
I think it safe to say it was Flaxen yellow, is there anywhere you can scrape some paint or dirt to confirm this? Man good luck!!
P.S. My '59 is 703A, and just like Johnny Wah mentions, there are 2 703A's and when I had the paint shop mix the paint, well it musta been the other one, when I compared it to the firewall original paint, very faint differance but I could see it, don't think others noticed!
-----------------------------------------------
Correction here, Above I originally wrote "729L ("L" stands for tilt-cab, go figure?) Not so, the "L" in my book is in parenthesis which means it stands for Lucite type paint!