Basic Automotive thread Question

[Appaloosa]

This is probably a dumb question. but I would like to understand basic automotive threads better. for example, I'm replacing a fuel filter and lines on a 95 cavalier. the fuel lines are rusted to I'm replacing them all. My question stems from when I replaced the fuel filter I got the correct stock replacement that has a 3/8" slip on connection for the filter inlet, and what is listed as a 16mm x 1.5 female outlet. I'm refering to a fram G7315 (used on many cars).

So my question is what is the correct fitting to use on my new 3/8 steel fuel line tuning that runs from filter to engine? Is this a tapered pipe thread. When took apart the old filter it has a flared tube with an "o" ring. I also noticed that a standard 3/8" nut from 3/8" brake line threads into this but didn't seal.

do I need an SAE 45 flare fitting, pipe, or inverted flare?

any help on this topic would be greatly appreciated. thanks

 

[3500GMC]

It's a GM fuel line fitting deal. I've seen the 'O-ring to AN Flare' adapters but can't recall if there was one for 'o-ring to inverted flare'...which is what you need.

There are o-ring to barb adapters to be had. Not good for EFI pressure IMO..

No pipe threads (NPT) anywhere..

Some radiator and tubing shops can duplicate the o-ring bubble on plain steel line.. You can reuse the OE nut.

Or get new OE lines?