Pretty sure that the problem with these pickups is that the material they used wasn't /gasoline/ rated. For a number of years, tankers had been "switch loading" gasoline and diesel - one load of gasoline, one load of diesel.
Tankers never get completely empty doing this, so you get a few gallons of gasoline mixed in with a tanker load of diesel. And, I'm thinking that may well have caused plastics to have issues
Lets assume a tank holds 5000 gallons. At 6.9lbs per gallon of diesel (googled it) that's about 35k lbs. Reasonable for a truck to carry 35k lbs? Assume 5 gallons of gas was left in a tank. 5 gallons of gas out of 5000 gallons of diesel is .1%.