There you go! Previous owner wanted more power than the 105. Incidentally, the 105 really only produced about 90 HP. In 82 or 84, Chrysler discontinued the 105 and simply down-rated it to 90 to comply with NMMA regulations requiring horsepower to be measured at the prop. The block stud pattern for ALL four cylinder engines remained the same even after mercury started mounting it on their midleg. However, The mercury engines have no studs and a match plate is bolted to the block. SO: To make a long story short, Any Force block prior to 1994 will mount to your leg. However, with these blocks you also need the flywheel and complete ignition system.
Respectfully speaking, the two piece lower unit is regressive and slow. It is a poor design and props are difficult to get. Why not buy a whole used engine? Get a nice Force 120 and change the lower cowl, use a 105 cover, and use a 105 model number plate.inside the lower cowl. Then, for all intents you have powered the boat with a 105. Engine weight is the same so there are no worries there.
Look up Frank Acampora on youtube. I have a video there of a 125 with a 120 crankshaft on a 15 foot Glastron. (rated for 90) It does a solid 45 with no bad habits.
