you should get one from Lowrance or other Navico brand. I ordered my 3rd T as a Garmin part and found that the T's don't line up (linear) because the connector pins are rotated by 45-degrees on the Garmin. Fortunately the Lowrance starter kit includes a 1-foot connector cable so I used it between the T's of different brands and that allowed me to screw-mount all of them flush against a bulkhead.

I'd recommend you hook it all up before permanently running the cables though, to make sure it all works together. Running the long NMEA 2000 cable from the panel to the pedestal was a big job for me (would have been a lot easier for a smaller person).