I need to paint my 1959 D47U engine.  It looks like 4C4185 (old highway yellow) Cat paint is discontinued.  Has anyone tried the Rustoleum V7400 Alkyd Enamel paint?  Looks like they sell it in the "Old Caterpillar Yellow" color.   

www.rustoleum.com/product-catalog/indust...voc-dtm-alkyd-enamel

 

I sandblasted and in the process of repainting the same machine as you. I am trying the Rustoleum Old Cat Yellow. That stuff was really hard to come by last summer and only could find quarts. I am mixing it with some acetone, the cheap Magic Hardener from Tractor Supply and a cap of Japan Drier. (Found a recipe on youtube) Seems okay so far. The tractor sat out for a month last summer and is currently sitting outside the past month or so. I painted the engine the same way and so far it is holding up to diesel fuel running on it when we had trouble getting the fuel tower to seal properly. First time really had trouble but go figure.
The jury is still out on the Rustoleum. I would have used some Polane urethane paint from Sherwin Williams but they couldn't get the correct colors last summer but I would rather have used it since I paint a few jobs with that stuff that's in the weather.
There was another topic on this subject about a year ago and someone found a paint company that has a match as well but can't remember the manufacturer.
There are several on Youtube but I tried this recipe:

 

protec paints which is part of ppg coatings. do all the equipment enamels. in the common colours. you can also get a colour mixed at any paint shop that does industrial or automotive paint. if they do industrial they do automotive and many that do automotive do industrial. highway yellow is a us dept of transport standard colour. any company can supply mixed colour. alkyd enamel works very well.
2 pack is tougher and more fuel resistant. isocyanates are nasty you can get iso free formulations but thats more expensive.
you can improve enamels with a dash of enamel hardener.works well price/safer to use wise.

the secret to a good paint job is CLEANING. it must spotlessly free of dirt, grease and silicones. oh and dont use acetone in enamel paint you will ruin it. use enamel thinners or mineral turpntine.

with 2 pack its very important to use the right hardner and thinner.

to save some money and get a really good job use 2 pack etch primer and single pack enamel for the top coat

I tried finding the Rustoleum Highway Yellow without much luck.  I did find this from Ag Specialties here in the US.  The color seems right, and they stock it in gallons, quarts and spray cans.

The ppg coatings rings a bell in my mind of a person from a paint company a few years ago looking to get the yellow shade right. Might not still being doing it but had contact information to buy product if I remember correctly. If some computer wiz could find it here in discussion, or was it a add in the for sale?

eh bare and company(bareco) have allsorts of tractor and ag parts they also have a range of equipment enamels in various colours. there is probably a stockist near you particularly in rural areas.