I have a 1994 Evinrude 120hp which has been mounted to a 18' Wellcraft center console with a 2' extended transom. Had several electrical and fuel delivery issues, but now are all resolved / repaired. Motor is now running excellent but mid-section / shaft length is too short for boat it is mounted to. On plane lower unit sits too high in water and has a tendancy to cavitate heavily and exsessively. Only way to stop cavitation is to slow down and / or trim motor down as low as possible, which results in motor basically pushing bow down, reducing rpm's and is basically "under" the boat. Motor is mounted as low as possible on transom and on initial take off, powerhead cover goes under water. From all my calculations, need a 25" shaft as apposed to the 20" on motor now to raise power head some and lower foot eliminating both "issues". My question, what mid-section / lower units will work with exsisting power head? Yr? make? model? I am hoping to find a blown motor with 25" shaft I can do a swap with. Thanks.