More studying harnesses; it thrus out my ADS=B system comes with an additional 3 serial ports. I needed one more port to feed the ELT with GPS position, so GRT walked-me through setting up a port that turns out is kinda dedicated for this purpose.
Cut some more wires, installed crimp-on DB25 socket pins for the magnetometer to fit into the EFIS harness. Used my new crimpers. Worked well!
Figured out installation spot for ADS-B system; I'll put on top of the map box; it will be accessible if I pull out the EIS.
Found out I forgot to install an extra lead in the EFIS harness for my backup battery, so I was glad I didn't button that up yet.
Getting close to the time when I'll need to install in the airframe.