MSD uses a silicone coating on their electronics to help move heat to the case so it can be dissipated.
The silicone also works to help keep moisture out of the circuits.
It's very moisture resistant, but not 'moisture proof'....
The logical thing to do is to mount the MSD box upright, so the one piece case makes an air bubble around the electronics.
A little shot of something like blue or clear RTV at the wiring grommets isn't a bad idea.
I've used mine around here, (we go 'mudding' a lot), for ten years with no problems.
It's been under water a half a dozen times in the back water at the river, and I've never had a problem one with it.
If you are going to ford rivers, mount the stupid box above the water line!!
It will go under for short periods, but if you stall or spend a long time in the water, you may have problems.
Also, people like to mount them edge ways, like on the firewall, then go deep fording...
That allows an easy escape for the otherwise trapped air bubble, and they will fill up then...
You may want to keep that in mind.
There is the Off Road module, and it is COMPLETELY moisture sealed. Even the wiring harness is weather sealed.
If you do something where you are in the water a lot, try the MARINE module. It's a 6 series module for marine applications, and it's completely epoxy resin sealed.
You can mount that sucker below the water line, and it wouldn't make any difference.
Figure out your application, and pick the unit you need. Believe me, they make one for you!!
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