Not sure where that coil is located so I can't answer ya - should be on the workshop CD. Or crack the drain plug with a 3/8" drive ratchet and see what color the fluid is and compare to a bottle of RP.

I have a hard time believing you got a mileage boost when all front end components and drive shaft were still turning even with the TOD clutch out. Those of us with TOD switches have not seen much if any increase in mileage when off.