This is not a completely accurate statement. While the firing order numbers themselves are different (1-5-4-2-6-3-7-8 vs 1-8-4-3-6-5-7-2), the pattern of cylinders fired if you draw it out is actually the same, only offset by sequence position (Ford 1-5, GM/Mopar 2 back around to 1). The difference is due to cylinder numbering. That being said, the difference would occur on Ford engines with the 351/302HO firing order (1-3-7-2-6-5-4-8 ). But, the same principle still exists where two cylinders on the same bank fire one after the next.