I can’t recall which posting it was a question about replacing the site glass tubing. The photograph showed what looked to me to be reinforced water hose.
The question on the form was what were the dimensions of the tubing. I can’t find the post. (Was just looking at it! 🤣🤣🤣🤣🤣🥴
We replaced ours on our ‘03 42EU couple of years back.
The dimensions on the tubing was 1/2 OD, 3/8” ID. Tygon tubing rated for Diesel fuels.
Attached is the receipt where it was purchased. I hope this helps.