I should also mention that my 'prep' of the surface before painting was limited to knocking any dirt or sand off the truck with a broom.
My original motivation for painting the truck was largely the same as the original poster in this thread.. the truck had a glaze of surface rust on it, and I just wanted to put something on the truck to help prevent any additional rust.
That and my wife wouldn't shut up about how stupid I was for trading the '67 for what she called a 'rusty old pile of s#it'.
What it looked like pre-paint job So being famously broke all the time, and having a low tolerance for my wife complaining about yet another hunk of junk in the lawn, I needed something I could apply fast, right out in the yard on a windy day.
Which is why I went with the paintbrush method instead of the spray cans.. spray cans in the wind ain't no fun.. and using the brush kept me from having to take the time to mask anything off.
I'm confident that had I taken a little more care in the prep and application phases, it would have come out looking 10x better.. and dare I submit.. good enough for a 'daily driver' paintjob.