Re: 1988 force 125
Well, It's not quite that simple--- For example, Force has a 4 inch gearcase and prop hub and bigger Mercs and Evinrude/Johnson have a 4 1/2 inch hub. So even though the splines are the same, the prop will not fit. HOWEVER: Some midsize (around 90hp) Merc engines have a 4 inch gearcase and those props will fit.
One thing I have been wanting to try: Michigan brand props sometimes have the same Michigan number for say a Force and (I think) Honda. SO if the michigan number is the same, then the prop casting should be the same and thus by inference other brands that fit Honda should also fit Force--even though not listed as a Force prop.