It probably is. ( oops.....it is probably a gas with electronic ignition. Not EMP proof) That is about the time they added electronics to Diesel engines. Starters are pretty safe alternators not so much but probably not a lot of other electronics on the engine. My Duramax and 1973 6.5 have electronics in the fuel management system that would debilitate them.I have a 67 F250 which is a backup truck we have always wondered how emp proof it was. Not just from the heavy steel but lack of not many electronics that if fried could be replaced fairly easily but I never looked past it that far.