So... my, new to me last Spring, 1987 34 appears to need the transmission "fixed" and I would like the opinion from those that know more about this than I do which, probably includes everyone that's a member of this great org... I say that because this is my first boat since I sold my 16' Hobie 30+ years ago so, I have
much to learn. I've sailed occassionally with others and been on a 2 week cruise on a Gulfstar 52 in the Abacos 25 years ago and a 2 week cruise in the Virgin Islands on a Hunter 42 15 years ago so, the love of sailing has always been there. Just needed the time and resources to get one of my own.

Following paragraph is the lengthy background. To get to the question, skip to the next paragraph

The boat was re-powered 10 years ago by a PO with a M25XPB / ZF5M transmission. I bought it with 450 hours on it. Yes, had it inspected and nothing reported about the tranny. Not having any previous experience as an owner/skipper, I didn't notice that the "feel" when shifting in to fwd was different than rev. Kind of slide in to fwd, firm engagement when going to rev. That came to mind when I wondered why it didn't begin to move fwd when I shifted to fwd after backing out of my slip mid-season a couple times. I began to do some research and looking and I believe the tranny is toast or nearly toast or the following reasons. A big oversight on my part was not checking tranny fluid right after buying. I did the oil, fuel filters and everything I could think of for the engine but neglected the tranny. Well, when I checked, no evidence that the fluid had ever been changed. Factory paint undisturbed. Checked dip stick and no fluid. Drained and found thick burnt fluid to no surprise. I filled with new fluid, ran to get to get it warm, shifted a few times then changed again. Tranny shifts a little better but, I don't think I can trust it. I'm open opinions on this.
So, my research shows it'll be little savings to rebuild the ZF5 and likely far better to go with a brand new ZF10M, if I can get one since they are recently discontinued, or go with a ZF12M. I'm not going by the inflated price for the 10 on CatalinaDirect. I'm inclined to go with a 12 but the ratio gives me pause. Going from 2.05 to 2.14. Am I making much ado about nothing? BTW, I'm aware the 10 is about an inch longer than the 5 and the 12 about 1-1/2 inches longer than the 5 so, I'm assuming I should probably have the shaft shortened to accomodate either instead of asking more of the Cutlass bearing which also must be replaced while the boat is on the hard for the winter.
Thanks in advance to everyone for your input on this and for all the great info I've obatined from this group!!!
-Bill