Smart Craft gauges

[Brummo]

I have a 2011 75 Optimax and am thinking about Smart Craft gauges. My question is, do I need to have both the Tach and Speedo to get all of the info from my engine or can I just get one? I have a 2011 Traker 175TXW with Tach and Speedo now. was thinking of replacing just the speedo.
What are the part numbers, if known, for the parts to run off this engine?

Thanks for any info!
Rob

[boats.net]

Go to MercMonitor | Mercury Marine and then decide if you want all digital gauges or the SC1000 gauges, then can choose the network you want.

[Brummo]

I guess what I'm looking for is, which gauge will give me all of my motor monitoring info. Will I need both SC gauges, or will 1 Merc monitor gauge do it all? Is one set-up more expensive than the other? If anything the tach gauge would have the most info, but am unsure if the speedo and tach work as one unit.
Thanks

[boats.net]

Merc Monitor will have all data but is small gauge and may not be able to display on data you want on one page. SC gauge has digital display at bottom and analog style at top but would best to use Tach and Speedo set. That link will list all data that gauge will display.