Gasoline odor no visible leaks

[82Cecil]

SWB C10 stock 6.0 liter, with 1 3/4" headers and 3" inch exhaust. using fuel cell above the bed. new steel braided fuel lines. Aeromotive A1000 on frame.

The oder seems to be coming from the rear and below but there are no seepages around the fittings. The AN fittings do have a small hole in them but I'm grabbing at straws with that. I would think if this had anything to do with the odor, liquid would soon be present.

After letting it set for 3 days the oder is still stong. the fuel cell vent is capped.

Engine has had a performance tune recently but the oder was present before the tune. I've sniffed the exhaust, it does not appear to be the source

Any ideas ??

Any tools that would help locate the source of the odor? (not a lighter)

Thanks for your help.