27 years is a lot longer than any I've had. The current one in the Post is not the original, there is a second, different, set of screw holes and mount tab pattern so it has to have been replaced once already.
I must admit that a fresh water boat has significantly less maintenance required. I'm still running original air units, none of the engine cooling system needs cleaning or replacing in this environment as well. My EZ2CY enclosure lasted 21 years before I replaced it. And only because it was getting pretty dingy looking. I love fresh water!
A luxury for sure, however good luck getting to any of the top Marlin waters, via fresh water. Some are built with salt water use anticipated and can therefore "enjoy" a good long life. Previous Bertram had both original 1979 AC units still blowing cold when sold last year. The three units in current newer boat were replaced for non salt water related reasons.