Re: mercury and force lower units !!
Maybe! From around '95 and up, Mercury-designed lower units and Mercury ignition electronics (ADI Ign.) were used in the Force 120's.
If you look up the part number for the driveshafts on any number of Merc Big 4 and Big 3 Inlines, they are the same (45-43031A1) as the driveshaft for your '97 120. The part # listed is for a Longshaft motor, just as an example.
If you look at the diagrams for your lower unit and any of the 70-75-80-90hp 3-cyl family, or the 4-cyl family of 100, 115, 125hp, and compare to the diagram for your lower unit, they look identical.
And all of the above belong to the same basic gearcase group, part # 1667-9011.
So I'd say there's at least a chance that something Merc will match up. There may be some slight differences in gear ratios but that's not a big deal, you can adjust to suit your boat by changing prop pitch.
Ideally you'd find one with the same gear ratio as yours, but if you were to find a Smokin' Hot deal it'd be cheaper to change or re-pitch the prop to match.
HTH.......ed
