I recently had my '92 244's fuel sending unit replaced to address the problem of fuel fumes inside the car. Now when I drive down the road and roll down a window, I smell fresh gas, as if it's being brought in from outside the car (and not through the trunk).

I crawled under the car and sniffed around. There's a strong fresh fuel smell coming from the right rear of the fuel tank. There's no evidence of fuel on the ground, so maybe there's an opening at the top of the tank.

Is this a common problem? Is changing the tank difficult? Where would I look for a new tank? I checked online, but didn't see any. How does one dispose of a used fuel tank?