Hi, First be sure the boat manufacture hasn't already ran the can line between the engine and helm. Lately I've been reading that some of the later model boats equipped with Mercury engines seem to have the line already ran. If not then you'll need the can line and install it yourself.
Looking at the three ebay sellers in the following link for the kit part number your interested in, the first one for $409.50 comes with a 20ft blue can line while the other two do not. 20' CAN Harness Part# 879982T20.
http://www.ebay.com/sch/i.html?_fro...X79-8m0062377.TRS0&_nkw=79-8m0062377&_sacat=0
If you don't already have the blue can line, then you'll need one, if you do then

. < Either way kit part number 79-8m0062377 is a nice kit.
btw, if interested, There is a ton of really great smartcraft and NMEA info/techs that can be found both @ bbc and continuouswave.com that will be able help you out a lot.
If you end up needing to run a can line in a tight spot then you'll need to read the following link,
http://www.bbcboards.net/mercury-3-...w-disassemble-smartcraft-cable-connector.html
Just in case here is some info about NMEA,
http://www.lowrance.com/Global/Lowrance/Documents/NMEA/Mercury_Engine_NMEA2000_Connection.pdf
Please let us know how it all turns out and good luck.