That gas station I worked at was a Mobil.
We had a Hostess bread truck and a US Mail privet carrier (under contract with the US Mail for that specific route) 1 ton truck that both got parked in the garage at the gas station every night. Both trucks left the building early in the morning. The bread truck arrived back at the Station around 3pm was was parked on the side lot until it was driven in every evening by the closing crew. The Mail truck did a 167 mile route to the smaller towns in our area twice a day. The first time was early morning, and the second time he pulled out every afternoon about 3pm for the same evening route, and was usually back at the station by 5 or 6 PM. When ever those two trucks came in, we had to fill them with gas, and park them on the side lot as well as put them in every night. Both trucks were manual transmission trucks. There was always two pump jockeys that worked the closing shift. If at least one of them didn't know how to drive a stick, they learned on one of those trucks.
The Mail truck was always pretty new, because of the miles the truck saw everyday, it didn't take more then a couple years to accumulate a ton of miles on it. When the trucks reached the 200K mile mark, he would just order a new truck, after the new truck was fitted with the required box, it was picked up and driven on the route the next morning. The guy favored Chevy or GMC trucks, over the 7 years I worked there he had a couple of each.
The 1st year that GM offered the HEI system on trucks, the Mail guy bought the 1st 1 ton Chevy truck in the area (and maybe in the country) with the HEI on it. It was a great selling point, can you imagine how many sets of points you put in a car in 200K miles? He was doing more then that every 2 years. Because of the miles it was driven every day, it was also the 1st HEI system in the country that failed! It was out of warranty at that point, but because it was a US Post Office contracted vehicle, it garnered the local Chevy truck dealer involvement, and after a few days being down, GM got involved (remember, this was the first real on the road failure of their "new" ignition system). GM provided a loaner truck so the Mail route was completed every day until that truck was fixed (it took about 2 weeks to get it going again).
Because my boss was a certified mechanics teacher, everything that the local dealership did, and everything GM did was done at our gas station. Because I was wearing a mechanics shirt there, and being the youngest guy at the station (and the most able to climb into and out of the engine compartment of most everyone there), I too was involved hands on, it was a fascinating experience! I bet we walked through their troubleshooting procedure each time a new guy showed up (there were a lot of new guys showing up every day). Those guys (and me) swapped almost everything in that system attempting to find the problem. Everything was done, one piece at a time, they had to find out what the issue was. That meant everything swapped in also had to be replaced with the old part again. After two weeks, it still didn't run, so we made a list of everything we had swapped out. The ONLY thing that was reused through the entire process was the rotor! I have no ides how we missed that, but at my suggestion we put in a new distributor rotor (We all figured we had nothing to loose at that point). The motor fired right up. Everyone was dumbfounded. I had to put the old rotor back in to make sure that was the problem. It wouldn't fire on the old rotor, but would fire on the new rotor. We had to handle that old rotor very carefully, they wanted to use it to test every other part. We had to swap each new piece we had installed back to the old original stuff (one piece at a time) and test it with both the old rotor and the new rotor. Every single time it would fire with the new rotor and not fire with the old rotor. After everything that was on the truck when it came in on the hook with was back on the truck, the rotor was the only thing that made the difference between it running and it not running. lots of guys looked at the defective rotor and we all determined that the spark was blowing through the rotor and grounding on the mechanical advance plate under it.
We were told that about a month later, another vehicle with the HEI system was hauled into a dealership with no spark, and they were told by GM to change the rotor and that vehicle also fired right up. Gm notified all their dealerships about the rotor issue and were advised to start with replacing the rotors first, then proceed with the troubleshooting process if the rotor did not solve the issue.
My only claim to fame was being on that team that discovered that weakness in the GM HEI system.