The '91 2.3 Ranger im working on has two coil packs. One where the later coil packs are, on the exhaust side of the engine. Then there is one that is tucked away on the driver side almost hidden. I want to do the dual coil mod where both plugs spark at the end of the compression stroke but i need to know which pack does what.

drivers side is compression. Passenger side is exhaust

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2004 Ext Cab, 4WD, 4.0, Auto, 154k. (4.0 engine is out of a 2009 Ranger w/96k) ( as of 7/1/2017)

2004 Ranger, Ext Cab, 2WD, 3.0, 5 speed , 4WABS, crank windows, no cruise, Edge 116k.(6/5,2014) (SOLD).
1999 Ford Ranger, Reg Cab, 2.5, 5 speed, 2WD, no AC, 150k (SOLD).