I have had vapor lock in my stock '51 Chevy half ton one time. I was driving to Kansas City and stopped in Eastern AZ in Springerville for lunch. After lunch, the engine stumbled and stalled a bit, so I pulled over and raised the hood. The glass bowl of the fuel pump was boiling like a tea kettle. The temperature was just above 90 degrees and just as important I was at 7000 feet elevation. Once I got going down the highway again I had no further problems. Within an hour or so I crossed the continental divide at 7800 feet with no problem, but I didn't stop.
I have driven the truck in temps as warm as 116 without a problem but that is at my home in Mesa, elevation 1100 feet.
Kent