[CA] [CA11] st60 tridata trans to C80 MFD

[cooltime]

Good morning, first post for me, so it may be a bit long.I will admit I have trouble understanding this tech stuff.

Installed instruments all about 2002 vintage include, two transducers, one speed and temp, one depth connected to the st60 tridata, C80 mfd,Garmin gpsmap 942xs and a small white raymarine junction box. Tried to add a pic of a drawing I made of the wiring, but no luck, would not allow that type of file.

Can I connect from the st60 to the C80 and get a fish finder type display on the c80. If so how.
There are two sea talk ports on the tridata, one is used to feed the 12v power., the other is unused.
In the junction box are two cables in, one out to the C80 sea talk port.
The two in consist of one from a 12v source, and one from the GPS antenna on the arch....all appear to be wired correctly according to what I have seen and read.....y to y / r to r / b to b shielding there.
Can the trans that is there be connected to the Garmin somehow ?
Thanks in advance.