Interesting Rick, I recall I looking at a parts diagram for the OMC KC cone clutch and found out that they did use an ESA. Not sure why but I was surprised by it.
I sure looked through a lot of the diagrams! Starting in 1990 model year (7.4L, 7.5L ), the "Interim" Cones have an "Interrupter" but no ESA. Makes me think they thought "Cones" needed only an ignition interrupt.
In 90, the the only Cones were the 7.4 & 7.5 The smaller engines (5.8L and smaller) were dogs.
Only saw ESAs on the Dog models....
In 91, the 7.4L got the cone (and interrupter) and 2 models of the 5.7 were cone and 2 were dogs. (only the dogs had the ESA) there was no 7.5L engine from 91 on.
In 92, the 8.2L, 7.4L, *some* 5.8L engine/drives were Interim Cone and had the interrupter.....the rest (of the 5.8L) were dogs (and had ESAs)
And so on.........
It's interesting to note however that an EFI model such as 58FAPRJVB 1993 had a dog clutch drive, and a shift plate (like earlier ones but no ESA. It must be built into the ECM firmware.....
I didn't look at all of them. But it was pretty consistent. The interim cones had an "interrupter" and no shift plate where all the dogs had shift plates and ESAs (except the EFI dogs)
The point here is that I didn't find ANY cone clutch drives with ESAs nor any Dogs with shift interrupters.
Now, in 1994 when some of them started seeing SX drives. (572AGPMDA 1994 for example) There's an item in the list of part diagrams called "ENGINE WIRE HARNESS & SHIFT MODULE"
but there's no shift module in the parts diagram or list. I think that might be a misprint. And there's no ESA to be found! If you find one, point it out. That would be interesting to see!
I also didn't see a shift interrupter on the SXs either.
Maybe someone who speaks Volvo can point that one out...
I am no expert and I definitely could have missed something!........
All I did was look at nearly all the sterndrive parts diagrams at
http://epc.brp.com
Cheers,
Rick