The 525EFI gen2 and 600/700SCi with the connectors have the Interface build in in the main ECM. You need only the wire and the senders.

I test the engine conector with the digital trim sender wires. I conect the digital trim sender wire on my 525efi trim tab conector. If i trim my drive, the smartcarft shows me the tabs are moving. So i ordert the original trim tab senders. I messured the right place on some new 380S Tabs and installed them on my old 380S. I used a PPE fitting and heated it up for the right tread. I make my own T-wire from the engine conector to the 2 trim tabs. purple + , black/orange - , green orange Tab, green ? Tab other side. works fine.

hier are some pictures from what i found to conect the tabs if the engine have no cenection.