Hello! I have a 1999 Marlin 350 SF with Mercury Racing 380 K planes. They run off of a dual "BOW UP/BOW DOWN" switch mounted on the dash with NO indicator whatsoever. The boat is powered by a pair of
2013 Mercury Verado 300's that have the digital throttle shift binnacle. There are the regular Mercury Verado guages, but the boat is equipped with dual 12" Lowrance HDS 3 monitors. So far ALL of the motor
functions work with the Lowrance system including the motor trim. There is a TRIM TAB indicator on the Lowrance/Mercury screen but I can't seem to get the two to talk so the K Planes "talk" to the Lowrance monitor.
From what I have been told so far and have seen with my own eyes, there are sensors on the K Planes. Any help or ideas would be appreciated.

Most likely the engines don't have a tab input.

What would you recommend so I can have some sort of tab position monitor or gauge?

Probably the Livorsi led indicators. Not sure what else will accept the 0-5 v from the senders.

Thanks! I will check that out.