64 Lemans: Changing to new SS gas/brake lines, one pc....
 

...question: How tough is it/any tricks to doing full length, front-to-back SS gas line?...seems it is easy with body off...but i am 'body on'...any tricks or will it just fit in easily from undersides?

I recently replaced the front-to-back brake line on a 64 conv. Just put the car on 4 jacks stands and slide under. No issues. The gas line will be more difficult because it routes inside the frame at the front and makes two turns inside. I would suggest forcing a stiff wire through the frame first. Then put 8 to 10 inches of the wire inside the head end of the gas line. This will guide the end of the gas line forward and exit the frame at the proper place rather than getting hung up.

Was told by the guy I got my lines from that the 1 piece fuel line will not go in with body on. Must be cut in half.

I do not see an issue with cutting it except for the 100% correct guys. I have used these fittings at work for 30 years.
Some $$$ but a perfect part for what you are doing.

Cut the line, install one of these fittings, and tighten it up. IT WILL NEVER LEAK. DESIGNED FOR HUNDREDS OF PSI WORKING PRESSURE.

https://www.swagelok.com/en/catalog/...?part=SS-600-6

Tom V.

You will cut the gas line slightly shorter on one section so that the overall length is still the same (with the fitting attached).

I replaced my 66 hardtop line years ago with the body on and did not cut it. You need to put the front half in and up through the frame first. If it was shipped to you, it's bent in half already when you get it. Don't straighten it all the way until you are feeding the back half up over the frame with the front half already in the car.