I suppose because you can buy one anywhere.
I suppose because you can buy one anywhere.As Dave said there are marine starter relays with isolated mounts.
There are also lots of lawn and garden tractor starter relays with isolated mounts.
Why the Ford relay with grounded mount became the go to replacement is strange.
I like to use what are called a continuous duty solenoids. Learned about them working with snowplows. Here is the thing a starter solenoid is and never will be intended to be continuously activated its supposed to be activated for short spans of time just enough to fire the engine up. But if you were to use that starter solenoid to run a snow plow lift pump it wouldn't hold up it would deteriorate quickly due to overheating because you are constantly activating the plow pump motor which is why they require continuous duty rated solenoidThat's a good idea about usage of the "I" connection, that is if one were to worry about not hearing the starter staying engaged. It's not a very loud sound, so I will strongly consider that option. On the solenoid, I did isolate the base, and attached the clutch diode wire (green/red - ground) to the base. I also cut off the two mounting wings to make installation easier. The instructions do indicate "M" and "B" connections (stater and battery), so I connected them accordingly. Did have to drill out the holes on the ring terminals that went to the battery and the starter to make them a tad bigger to fit on the larger posts on the new solenoid. I changed the other ring terminals that go to my key switch and accessories to larger ones, (I have the dogbone eliminated). The starter button wire and the ground clutch diode wire I had to cut loose from the connector and add ring terminals, of course. Waiting on my replacement starter. But I can tell the solenoid is different. It's instantaneous in it's action and release. I've read a lot of good stuff about this solenoid. And also about the marine one, but not as much. Cars and trucks are in use more than boats may be the reason. In either case, both are much better by far than the cheap a.. solenoid I had on there. Just a note, never buy a cheap solenoid. Too many amps going through there.