OMC vs. Mercury Instrument Signals

[Alastair Moffat]

I have just had to scrap a 1991 Evinrude XP 150 hp 90 degree V6, engine number 2403539. The block has corroded to point of no repair (400+ hours in seawater, always flushed after use but apparently these blocks have a reputation for casting porosity and metal loss). The instruments are still in perfect condition. I have bought a replacement Mercury 200 hp, 60 degree V6, 1983 model, with 220 hours and only ever used on a freshwater lake. I was wondering if anyone could advise on how compatible the instruments are, specifically, the rev counter and temperature gauge (e.g - are they 4-20 mA signals or 0-9 V signals?). The guages for the new motor don't match well and are looking old. The OMC motor also has a trim indicator. The Merc doesn't - could one be fitted and the trim gauge used? The dealer that I am buying the motor from says it is a 1983, but the starter motor is stamped April 1980 - does this mean anything?