[Yo-Yo]

Ford diesel pickups are EMP proof through 1994 - they have an all-mechanical injection system.

I wouldn't bet the farm on Ford diesel pickups. If it has OBD it is susceptible no matter if it is mechanical or electronic injection.

[Spktyr]

The IDI engined trucks don’t have OBD at all. There are zero electronic controls on the IDI diesels and once started you can actually remove the battery and disconnect the alternator entirely. Ford diesels didn’t get engine OBD until the 94.5 model year trucks and the PowerStroke 7.3L engine.