Many newer models do have an isolater as standard equipment. I can't qualify newer because I don't in what year they started the practice.
I did pull up the owners manual for your boat in the archives section of the Sea Ray website and it did not show a galvanic isolator in the schematics, or mention the existence of one elsewhere in the manual.
All I could advise you to do would be to start at the shore power plug and start working your to the AC panel and see if you bump into one....
I know mine doesn't have one - I've virtually rebuilt the boat, including rewiring all the shore power. I'm not even sure they were making those things in 1980. I'm just curious about current models. I'm thinking about adding one.
Well now you guys have me doing some head scratching???
On my 2002 240DA an isolator is listed in the specs, shown on the schematic in the manual, but I have not been able to put a visual on it. I called Sea Ray on the subject, they said the isolator was mounted behind the port side finish bulkhead in the stern locker that the shore power plug and breaker are mounted on. However, short of tearing that whole side of the stern locker apart there is know way to verify the existence of the isolator. I wish I could figure out an easier way to verify as we were fighting some corrosion issues last season. thunderbird1, FYI, a galvanic isolator is listed in specs, shown in the schematic, and stated in the manual to be mounted behind the microwave in the galley for your 260. Don't know if Sea Ray jipped you out of one or what???
Thunderbird1 the galvanic isolator is also listed in the parts breakdown as a "not shown" item. Its on p43 on the left side. I also found it on the wiring diagram for the main distrubution panel p6.33 (without gen) and p6.34 (with gen).
You pose a great question. I hope we hear some responses.....
I was told by Sea Ray that at least in the case of our 240 that the isolator used was vended from Mercury Marine. Can't confirm, or deny.