Re: Johnson 175 what year?
Sorry, that reveals nothing. Look on the port (left) transom bracket for a plate that would contain the model & serial number. The model number is what is needed.
If a late model engine, that plate may simply be a heavy duty decal located at the top port area of the swivel bracket that the engine turns on.
Also, look for a small quarter sized core plug (looks like a small freeze out plug) on top of the powerhead, usually near the port cylinder head gasket.