i have a major issue. the fuel return line on my 82 Z28 was stuck. so when i pulled the motor i cut the line while in the process it shredded the fitting. and now that im trying to rebuild the line i cant find the fitting anywhere. and better yet i cant get Neither NPT or AN fittings to work. does anybody know what the fitting thread size is or where i can find it. i have the big fitting that is direct to the throttle body its the one on the actual line that i need. id prefer to make a steel braided return line because thats what ive done for everything else so far but i will work with a regular stainless line if needed. please help

 

I had a crossfire on my 84 vette, the return line was a double flare (no o ring) type, the line is probably the same as those 5/16 lines at the parts stores, US thread.
Remove the fitting from the throttle body & take it with you to the parts store.