Guy needs to learn mathematics. A 1991 car is 28 years old this year. One of his underneath photos is upside down, but we can fix that. I'm guessing that Chevy did not use hose clamps and rubber pieces on the gas tank filler tube? I could be wrong, but that seems unlikely, and it's a bit scary. And for pity's sake, how about clearing the trash out of the car before taking the photos? Slob.
I can kind of understand a non-detailed vehicle if it’s a family member selling a loved ones car. Where they literally back it out of the garage and slap a for sale sign on it. Maybe the family members are not car people and are afraid to wash uncle Jim’s beloved Caddy that’s been sitting for a year. But when you have a “I know what I have” ad like this Olds, he is obviously a slob and I wouldn’t trust a word he says. And while he mentioned the spare tire well, there looks to be some good scale on the frame; I bet the engine bay is a rusty mess.
Aside from the fact that the hose clamps are about 10 sizes too big I don't see anything wrong with that setup. There is probably a nipple coming off the tank and they needed a way to join it with the filler pipe. The tanks on my T-Birds and Cougars have a very similar connecting joint on them. I know because it is such a pain to disconnect from the filler tube every time I have to drop the tank.
The hose clamp setup is actually what's on my Diesel Suburban now. I don't recall any rust under the hose but I appreciate Jaunty's observation.