ACCEL Spark Plug - 14 mm Thread - 0.708 in R - Tapered Seat - Resistor - Set of 4 62100011 1987-1996 Ford F-250

1987-1996 Ford F-250

3/8-16 thread

Various GM Applications 1998-2006

Only the dog ring is used to make the shift

ACCEL Spark Plug - 14 mm Thread - 0.708 in R - Tapered Seat - Resistor - Set of 4 62100011 1987-1996 Ford F-250ACCEL U Groove Spark plugs have set the standard for High Performance Spark Plugs. ACCEL Engineers developed and patented the U Groove technology which permitted the spark to develop a much larger, hotter and fuller flash front. That effectively gave a more complete burn of the air fuel mixture in the combustion chamber. Over the past 25 years engine head design and fuel management technology has changed. As a result, ACCEL is moving away from the U