Sure many have replaced their alternators
Here's my story:Equipment Selection: Alternator - I evaluated all the different alternator possibilities, including Balmar, Leece Neville, and Battery Shack, which makes both internally and externally regulated alternators. I selected the externally regulated Blue Circle Delco small case 100 Amp unit Model M-7102-HD, for $140 including S&H, phone 888-932-2423. This is the alternator described by Jim Moe in his excellent electrical system article in the website Projects section. It fits perfectly without having to modify the alternator bracket in any way. We’d upgraded the alternator bracket on our M25 in 1998. The M-7102-HD is plug-and-play with any of the new smart regulators. Jim Moe recently reported that Blue Circle also now has a 75 Amp unit, M-7102, for less money (approx. $110) for those who choose to select a less expensive model. Either choice is significantly superior to the 55 Amp OEM unit with the relatively useless internally regulated automotive regulator. Regulator - I purchased a Balmar Max Charge MC-612 for $280 at a boat show. Wiring, heat shrink and lugs, two new belts, a Mega Fuse and holder, the backup ACR, the ground bus, and fasteners cost just under $300.********************That was an excerpt from my Nov. 2006 Mainsheet C34 Tech Notes article, which included a wiring diagram.Review these C34 website articles:http://www.c34.org/projects/projects-electrical-system-upgrade-2.htmlhttp://www.c34.org/projects/projects-electrical-system-upgrade.htmlThe C36 website (www.catalina36.org) also has a good one, with a reference to Leece Neville.