Trying to find fuel leak

Hello,
I am hoping someone may have had the same problem that I have with my 69 Dart so they can tell me how to fix it.
On a recent trip it (273 V8) used half a tank of gas in an hour. This seemed rather excessive and also we noticed that there was the smell of gas in the car.
Obviously it has a gas leak somewhere. Got the car on a hoist and checked everything. Could not find any signs of a leak.
It has a new tank and sender and there are no leak stains.
I had some gas in a jerry can so I filled the car in my garage. The garage smelt like gas for quite a while. But once again there was no obvious sign of a leak and I did not start the car or have it running.
Any ideas you have would be appreciated.
Thanks, Ron.