Reply to "Gas vapors"

You're right to be concerned; if you can smell it, it can ignite! The Pantera uses a sealed cap and a vented tank. Fuel vapors from a full tank will come from only a few places. All of them require you to remove the engine screen and left side cover, and carefully look for stains from fuel leaks.
First, the large diameter hose attaching the outside filler to the tank fitting (on '73-up cars). Many owners don't realize that this hose needs to be fuel-proof; ordinary radiator hose lasts about 2 years, then shrinks & splits. This hose often splits underneath since the two halves aren't closely aligned so the hose is strained. Makes finding the leak a little harder.
Second is the vapor vent valve on top of the tank: this dome-shaped thingy can more safely be replaced with a fairly cheap anti-rollover valve. Mine came from Hall Pantera. The stock dome is pop-rivited to the tank, and sometimes, the rivits aren't there or aren't tight enough to compress the gasket. Sometimes, there is no gasket. FWIW, once the rivits are drilled out, the holes in the tank are factory-tapped for screws. There may also be cracks in the hose connecting the vent valve to the charcoal cannister, or if thats gone, to the air cleaner base. Venting to the atmosphere makes fumes you can smell. FWIW, those factory "steel-braided lines" are plain-vanilla rubber under that braid, and they crack & break just like all old rubber does with fuel.
Third is the fuel gauge sender; 6 screws hold the thing to the tank with a gasket underneath. Make sure the screws are tight & that the gasket isn't cracked.
Finally, on early cars, there's a fuel-out line welded into the tank that uses a metric banjo fitting. This fitting should have copper washers between the tank & banjo, and between banjo and hollow bolt. The banjo bolt should be tight. On late cars, the fuel-out line comes thru the sender with no banjo. Both have rubber lines that should be hose-clamped, and be newer than 1990- about the time the Feds mandated MTBE fuel additive. Besides its cancer-causing properties, this stuff attacks & ruins hoses made earlier than 1990. If you're not sure, replace 'em!
Other than a rust hole thru the tank under the hold-down strap, a loose drain plug or a stone chip that cracked the metal, thats about it. But there WILL definitely be a fuel stain somewhere.