We are working on a 84 f150 and the spark plugs are longer threaded than the ones we bought we replaced head gaskets. Someone said it mite be out of a car any help on what 302 we have.

 

Check the reach of the tips between the two plugs, and make sure they are the same. Some of the old plug models have been replaced with newer models, and while there might be differences in the threaded regions, they should put the tips at the same place.

 

Trucks and cars used the same heads in 302's. There were many different heads though. Identifying 302 heads can be a pain, if they're earlier than 1986 heads. 1986-on, there were 4 basic heads that all can be Id'd from the outside. Look at the lower front corner of the passenger side head, right next to the valve cover. E6SE heads have an "S" cast here. E7TE heads will have a "T". GT40 heads have "GT" here. GT40P heads have a "P" here. All the earlier heads are a little tougher to Id, an 84 302 would have D8OE heads with 5/8 spark plugs, these heads were used from 1977 to 1984 and all used the same plugs. The earlier 302 heads had the larger 13/16 plugs. The E6SE and GT40 heads used different plugs from all the other 5/8" plug heads. All the 13/16" lug heads used the same type plugs.