sealing a sending unit

[Gunnibronco]

I have to swap my rear tank out. I patched the tank fill tube a little more than a year ago with a Permatex patch kit (2 pt epoxy & some fiberglass). Its now leaking again.

I can't get a sending unit oring here in town, mine is probably 15 years old. One parts shop recommended using Right Stuff. I thought I'd probably reuse the old oring (if it comes out in one piece) and add Right Stuff, for good measure.

Our Ace hardware has a good selection of orings, but I wouldn't think they would hold up to gasoline exposure.

Any other recommendations?

I figure if it leaks, I'll order the right oring from a Bronco supplier, but I want to do this swap this weekend.

[Kinder]

If the original o ring is a survivor I'd reuse it by it self 1st, add right stuff for plan B, new if above fails.