there is a box-like piece on the driver-side of the gas tank tank of the 1970 stingray...with a hose leaving it.  it is apparently leaking gasoline, and neither myself, nor a professional mechanic, when feeling around up there, could find any bolts or anything holding it to the gas tank.  is this part of the gas tank itself?

It's possible they simply put the seal in wrong, it can be a little tricky. The leaking when it's full part is a bit weird though, since all the penetrationa are on the bottom of the tank. Maybe your shop owes you another look at it since you paid them to do a job in the first place. Is dropping the tank something you can do yourself? It's time consuming, but not overly difficult. Can you figure out what the mistry box on the side of the tank is? That still confuses me. Are you looking at the ground plate for the radio antenna? What looks like a hose may be the antenna lead. Having said that, if the tank only leaks when full, how full?Could the seam have separated?. Either way, I really feel like the tank should be removed for inspection. Keep in touch, if I can help, I will.

Anybody else here have any thoughts?

Still trying to figure this one out and had another thought. Does it leak when absolutely full? I had this on another vette. The seal at the filler neck could be bad. Remove the filler cap, then remove the rubber seal. The neck is screwed to the tank and has a gasket. If the gasket is bad and you have a completely full tank, it could slosh, or on a hot day, the fuel will expand and push past this gasket. It could then run down the tank to the lip at the seam and travel the seam to a low point and drip down. To fix this, you really don't need a new gasket, just clean the surface thoroughly and use a fuel resistant sealer to re-attach the filler neck.

Again, let me know. Guys??????????????

I just replcaed my feul tank on my 69. there were no fuel hoses on the drivers side.It could be the Vent tube coming from the top of thetank that could be routed down the drivers side. However, i couldn`t find the leak until i dropped the tank.I found a hole under the support bar on the forward part of the tank. the pressure from the full tank may force the gas out.

I suggest you drop the tank and inspect it.