[HAULIN' IT]

I'll add my thoughts...some of what I speculate & some factual. For sure the letters were painted on top of the base color of the truck originally.

Now onto the speculation (from many years in the autobody industry) & also some ideas of how to try to reproduce the effect.

For starters, the paint was an odd, rather transparent product & it appeared to be that one coat was sprayed & move on. You can see the actual "droplets" of paint collected together where the middle of the letters are more solid as it goes toward the edges. At one point, I considered they may be done like a printing press of sorts (rubber pad dunked in paint, then placed up to the truck) but like has been mentioned, Ive seen some WAY off of the raised peaks of the letters, but still mostly painted the right width of each letter...which couldnt happen that way. The last, script off to the side Chevrolet gates (81-87?) seemed to be rather bad for this shift (the smallest/thinnest of all of the gate letters). Once in a while you will see a "thinned" painted letter where say part of the H vertical is thin & the rest is normal which raises even more question.
Im going to explain how we reproduce the chip guard on the bottom of some of the vehicles nowdays that have a straight, but "soft" edge toward the bottom of the vehicle with the purpose of working back into the letters. On the panels hanging vertical as they are/would be on the vehicle we tape a row of 3/8" nuts an inch or so above where we want "the line". On top of the nuts we tape a straight piece of cardboard hanging down past the nuts (the nuts just keep the cardboard up off of the panel) & then spray a careful straight, level coat right at the cardboard & below. When done, you have a straight but not masked-off line with a soft edge.
Back to the letters, my guess is they had a 1/4" to 3/8" thick plastic "guide" with gummy/sticky stuff that held it to the gate (but not vinyl tape like we are used to seeing) with a thin outer layer holding the center of the O & R all in line. Once stuck down, the top layer would be removed & the letters sprayed. Then the plastic chunks removed. Done! The thickness does two things, it makes it easy to grab to remove (unlike a decal mask) & also fuzzes the edges. Paint wont go to the corners when applied straight on into a thick corner. I could be WAY OFF, but that is just my thoughts. We can discuss how I would go about trying to reproduce the "correct" effect if anyone is interested. Lorne