Woody,
THIS ENGINE? Are you referring to the color of one of those engines (there are 8 photos of maybe six different engines??).
The blue-colored engines are painted the blue that is more commonly associated with 54-62 passenger car engines (Blue Flame Six). They are all 54 or later engines (and number 8 has an interesting valve-cover decal).
Here is a 1954 truck engine painted Jim Carter gray (the oil filter is a 55-62 AC canister painted 55-62 colors).
Are photos 1-2 and 7 the pre-54 engines painted gray that you are referring to? Let's wait to hear from Denny on the pre-54 gray.
No offense to the VCCA or AACA arhivist/experts, but I doubt that anyone can be 100% sure that "their shade of gray, or dark-gray, or or blue-gray" for every/any/all 29-62 Chevrolet truck 6-cylinder is THE correct shade of gray.
Tim
