I'd like to pick up an Airguide tach to somewhat match the Airguide speedometer and clock that are original on my 50 yr. old boat. The problem I'm having is trying to determine which tach's will work w/1977 Evinrude 35hp. Does anyone have a copy of an old Airguide application guide they'd be willing to share, that may cover some of the older tach's that I see for sale?