Looking into purchasing a 998c SI Combo later part of this month and being most items i purchase are via the web I have a couple questions. Does the unit come with everyting necessary to install and start fishing; by everything I mean power cable, transducer, ECT. Being a rookie I really don't know whats included in the package and none of the websites I have found give a detailed list. Will be installing on a 20' CC Express Bay that came with a factory installed 365i Combo that I will be moving to the trolling motor. Would you think that the current location of the 365 transducer would work for the 998 transducer? Thanks in advance for your input.

The unit comes with the Side Imaging transducer, a power cord, a GPS antenna, gimbal mount with knobs, an accessory cable, and a cable collector to hold all the cable plugs to the display.
All of that is for a "standard" installation for craft world wide. Your boat may not be "standard".

Side Imaging is not your grandaddy's sonar. The location of the transducer is critical for the best performace. It should "see" horizontally left and right from the water surface to past vertical under the boat.
There is no one size fits all, you have to set it up for your specific hull and performace capabilities.

Yes it comes with what you need.Transducer Shield an Saver makes a nice bracket to mount the Ducer, if you got a jackplate

This is 1198c Standard Package just switch the head units and cable collector and you will have a 998c standard Package