Originally Posted by Trimix
Well I shall ask Suzuki and post up an "official" answer - seems everywhere I look on the interweb I get a variety of answers
The cost of the NEMA network cable from Garmin is a daft price in the UK, but in the States it much less. Ive a mate going there soon so I shall get him to bring me back one.
The internet is not - unfortunately - the best place to look for this sort of answer.
Basically both Garmin 750 S and Suzuki DF175 are both NEMA compatible, and in very simple terms you will need some sort of interface box and wiring between the engine and the plotter. In very simple terms the Suzuki SDS system feeds data into the NEMA 2000 plotter.
I would note that the Lowrance and Simrad plotters will (usually) connect directly to the Suzuki units - Garmin do not.
The reason that you have found/been given more than one possible solution is that the model year of your DF175 determines how the wiring connection will work. This makes a significant difference, as the wiring will be different between the analogue and digital instrument models of the DF175. As a starting point, in order to get the right wiring solution we would need to know the engine model number.