You can buy the 3 wire trim from ebasic power here

https://bpi.ebasicpower.com/search_2...q=wire+harness

but it doesn’t come in the cool old school yellow tracer loom. however buying this half wrap around nylon loom gives it a super clean look and easy to slide the wire into and isn’t 1980s corrugated plastic loom. In the link go down to the 3rd grouping and it says wrap around then it’s the first selection

https://www.mcmaster.com/#standard-c...eving/=1dk61dt

for 3 wire 16ga the 1/4” is perfect. You can squeeze it in 1/8 but you’ll be cussing. Also what you can do is route all your trim (2 tab and 1 drive pump) in a piece of 1/2” and as they branch off sleeve 1/4” into the 1/2 where the wires separate and a tie to hold them together.

the yellow tracer loom is old mercury stuff. When I rerigged my boat it had a fair bit of it in it from old trim pumps but when I relocated everything it was too short. But when you buy new merc kplane kits they give you new harnesses in the cheesy plastic split loom and I replaced it all with the self closing stuff. It’s super easy to work with. It says you do not need a cable tie to keep it closed but I found at the ends it helps keep it perfect with a small tie or Afew wraps of black electrical tape. However the tape over time leaves the nasty glue residue.