could not have said it better than MIKE just did.

in the early force/merc years. (and i may be wrong) the lower units used were still force lower units, with mercury powerhead parts????

NO . the mercury/force is again a completely different creature than the mercury/tracker deal.

Is it time to go fishing yet??

Have a 96 Force/Mercury and its been a good motor. At that time I was told that the only differences between the two was:
1. The horsepower rating in the Force was tested at the motor and the Mercury was at the prop.
2. The method of sending the spark to the cylinders was older design without the loop charged induction system or something like that.
Point #2 could be the difference you get w/ point #1.
Maybe its really a 70 hp at the prop on the dyno.
Bottom line is its been a good motor for me w/ hundreds of hours on it.

On most of the later force motors, the only difference is the merc has oil injection and the force doesn't.

I've got a '96 90 force, and it's a merc 90 in every way except the oil injection. NOTHING else is different.