[joey]

You can probably get away with an 1 1/4 " shaft if you went with a stronger Aquamet 22 or like material, coupled to a higher RPM turning diesel like a Yanmar.The lower turning higher tourqe engines like the Cummins will definately require the 1 1/2" shaft.Also,be sure that if you put say a Cummins in that there is enough room under the boat to swing the larger wheel that it will need.I was having the same issues with a carolina boat that I had and I really,really tried to put a Cummins in her,but after alot of research it would of been just to much of a pain.Larger shaft,stuffing box,strut,exhaust,plumbing,etc.The Yanmar is a drop in for a 350 gas engine,same engine foot print,no running gear change,if you have 4" exhaust no change there,you will probably swing the same wheel that you have or one very close because the Yanmar turns about the same rpm's as a gas engine.I'm not crazy about a 3800 rpm diesel,kind of defeats the purpose to me,but a lot of folks swear by them.Good luck with your repower.