Which engine?
for what size of engine ?
That would depend on which engine size you have
.044 inch ( all available size gas engines )
www.motorcraft.com shows (.044 inch ) plug gap on the 1989 F150 300 cubic inch ( 4.9 L ) straight 6 cylinder engine
( .054 inch ) according to www.motorcraft.com
passenger side of engine , front cylinder
The spark plug gap is .054"
The spark plug gap is .054"
Check the Vehicle Emission Control Information ( VECI ) decal located in the front of the engine compartment ( it will show what type of spark plugs to use and the spark plug gap )
www.motorcraft.com shows .054 inch
passenger side of engine , front spark plug The engine cylinders / spark plugs are numbered : passenger side of engine , front to rear , 1 , 2 , 3 -----drivers side of engine , front to rear , 4 , 5 , 6