Dirty little secret from merc... The mercruiser regulator is a dirt cheap keihin regulator out of a Honda car. Furthermore, the damper is just a regulator with the return port fitting blocked. Earlier motors used the same regulator but the return port fitting was open. That little open fitting is NLA from merc marine, if it wasn't I'd have one on the way.

I've contemplated messing with the fitting, drilling a hole in it, finding an o-ring and giving it a shot. But because of the oddball fittings I'll need for the back of the rail, if it doesn't work I may end up out 70 bucks for nothing.