I had a 2010 era (not exactly sure of year) 958c and terrova combo in the bow and tried grounding/ chokes etc. nothing really made it improve, if trolling motor was at 0 or 100 percent sonar worked great
Anywhere in between it barely read bottom
This yr I put a new ulterra on the same sonar and it works great

I bought a gen 2 ulterra that had Bluetooth controller and heading sensor already
Then I bought a link system and converted it which left the following leftover parts

Bluetooth head unit
Heading sensor
Remote
The little plastic dust cover for the head

So i had the parts for the upgrade left over

These components are $500 from hummingbird so yes this is a good deal

Global map is sold