You will know right away if both drives are not moving the same. Lost the trim solenoid on the port side of my 330 a few years ago, When I trimmed the boat it immediately listed to a side. At first it took me a bit to figure out what was happening, but for sure I knew something wasn't right.
I started with brand new analog senders when I rebuilt the transom assemblies on the 330, and set the gauges exact. That lasted for all of 3 weeks. They suck. Ignore em, and like I mentioned above you don't need them to drive the boat anyway.
However, the new digital senders on the smartcraft transom assemblies do actually work. Once you figure out the system and calibrations, they work great.