need info ona 75 tracker/force by merc mota

[boilerdawg]

my fishin partner just bought a boat. its a 98 tracker with a tracker 75 h.p. mota on it. in reality its a force made by merc. the model number on it is
H075412UT. he is tryin to find a prop for it. the problem is that the lower unit that is installed on this mota doesnt seem to be the right one. its smaller than what he thinks it should be. hes thinkin that cause hes seen "real" merc 75's with a different l.u. the one thats on there now has a 13 spline prop shaft, the one that he feels oughta be on there has a 15 spline shaft. does anyone out there have this mota? if so what l.u do you have on yours? and whats the gear ratio?
thanks
matt

[Riverratt]

he may be thinking of a bigfoot

[shadowman]

But I think Mercury used the older US Marine lowers on them for the first few years. Then they changed the mid and lower to Mercury made units.