If you go with the old school style gauges, you wont have any issues( dial or digital) what you don't want is any of the newer style CAN BUSS linked gauges( Command Link?). Anything with more than basic data is going to be CAN BUSS and wont work with your motor. . Most aftermarket gauges are old school and will work. As far as your mounting choices, I'm not sure what you are talking about. If you're speaking of a plate that goes on teh outside of teh boat, they are usually used if theres a transom issue. The inside the boat plate that goes between the top two bolts is fairly common and cant hurt. I had one for teh top two bolts and made one for the bottom two bolts.