Re: Fuel filter water drain fitting
Reply #1 –
That looks like a common 90 degree MPT x DOT Air Brake Compression fitting. The tube you are holding in the photo has the old steel insert still stuck in the end. The replacement fitting should come with a new steel insert, but you can sometimes reuse the old one. Just need to determine the correct thread size and the tubing size, then order online or can probably find one at a NAPA store. If in doubt, cut the end of the tubing off right above the nut, and take the end piece and nut in with you to the store.
You could also switch to a DOT "push-to-connect" type fitting that would accomplish the same thing. See 2nd photo.
Typical DOT fittings shown below: