of this loco? 
I believe UP’s colors are Armor yellow and Harbour mist grey.
If all else fails and you’re willing to mix your own paint you could always use dull flat yellow and medium gray…
Good luck.
Tracklayer
Hmmm…Yellow, grey, red, with maybe a little chrome, some silver and pewter?
Did I guess the colors?
Did I win? Did I?
[%-)]
Rotor
New Haven,
Here’s a link you should save and learn to use as it is a very powerful, useful tool:
Using that tool and typing in “Union Pacific paint colors” I found:
UP’s basic paint scheme for its diesel-electric locomotives is the oldest still in use by a major railroad. The bottom two-thirds of the locomotive body is painted Armour Yellow, so-named because it was the color used by the Armour meat company. A thin band of red divides this from the Harbor Mist Gray (a fairly light gray) used for the body and roof above that point. A red line is also painted at the bottom of the locomotive body, but this color has gradually become yellow as new FRA regulations for reflectorized tape came into effect in 2005; the trucks, underframe, fuel tanks and everything else beneath that line are also Harbor Mist Gray. Lettering and numbering are in red, with black outlines. Some locomotives (historically passenger locomotives, and some recent units from 2000 on) have white-outlined blue “wings” on the nose. More recently, some units have been repainted with a large, billowing Stars and Stripes with the corporate motto “Building America” on the side, where the ‘UNION PACIFIC’ lettering is normally positioned.
Don Z.
Maybe New Haven I-5 is colorblind…[swg]
No I’m not color blind. I know that it is gray, red, & yellow. I wanted to know what kind of gray or what kind of red or what kind of yellow.
I know! I was just kidding.[;)]
I seriously doubt that Wiki is correct here. All diesel trucks were painted in an aluminum color beginning around 1955-56 and I believe they are still aluminum colored.
Other than that, it seems correct. Several paint manufacturers make the Armour Yellow and Harbor Mist Gray, so just take you pick.
Per
Scalecoat 2 is the paint of choice here. Use their 22 U.P. Yellow and 32 U.P. Grey. Finish up with Testors Dullcote cut 50% with Scalecoat 2 thinner fo seal in the decals.
I agree, and as a matter of fact: http://www.uphs.org/Dieselpaint.htm (1957)
…and yes, 
is your friend.