I AM RESTORING A 16' STEURY SKI BOAT WITH A 60 HP JOHNSON SUPER SEA HORSE MOTOR. DOING WELL WITH EVERYTHING SO FAR, RUNS GREAT. I AM ONE WHO LIKES TO SEE WHAT IS GOING ON, AND PREFER GAUGES. I SEE RPM GAUGES FOR SALE IN A LOT OF PLACES. ARE THESE UNIVERSAL? IS IT DIFFICULT TO INSTALL ONE...