Tachometer/Outboard Compatibility help

[VeroWing]

Recently bought bought 20' Grady CC that originally had a 200hp Johnson/Evinrude on it, and before selling PO had a carbed 225 Mercury (199?ish) installed on it. Marina mechanic that did install said that he could not connect this Mercury engine to the existing boat's tachometer because they were not compatible. Is there any way this tach is workable to this engine, or should I purchase another one that will work, and if so, can someone suggest which model will work? From a previous thread here, it was determined that my engine is in the OG129222-OG303045 group, and I'm adding pics of tach and engine below. Aprreciate any help with this. Mike

 

[VeroWing]

Anyone have info on this?

 

[Faztbullet]

Must be a system check tach as wiring/connectors is different. Any aftermarket outboard tach will work.....

 

[VeroWing]

Thanks Faztbullet. I thought perhaps there was some sort of special tach to read the pulse from computer. Mike