gas tank vent

I have a 1936 C-30 stakebed truck that had a rusted fuel tank(under the front seat) I removed it for blasting,cleaning and rust proofing. The shop doing this called to enquire where was the vent. I didn't see one on the tank! I only removed the gas line and a couple of screws/bolts around the perimeter of the wood box that the tank sits in. There is a gauge in place(not functional and another access that appears to be about the same size as the gauge but is sealed shut. Should there not be a vent somewhere? please any help would be greatly appreciated. Thanx Brad in Virginia

No vent!
If there is, it's inside the filler neck.
Otherwise, no.

Thanks Smog guy, Someone on Yesterday's tractors said I definitely need to vent the tank. What do you think. It would seem to me that the thing would need it? Maybe the capd weren't that tightly sealed? Seems like the negative pressure would just build up and eventually stop the flow? Maybe not. I'd appreciate any further thoughts you might have. Brad

Yes, the gas cap is vented. It breathes.
No other vent is needed.
It's under seat, kinda scary as it is.

Thank you again smog guy. Do you happen to know where I could see an "original" cab fuel tank setup? the manual[i] lists upper and lower tank " straps" and atank "supports" none of which I believe to be present on my truck. I would like to fabricate something similar. Thanks, Brad

I have an original in the truck.
It's wet and miserable out, though. The truck is in rough original shape.
I don't know how much original stuff is still there.
But I'll be glad to take a picture..

Vented caps were the standard on vehicles and tractors until the late 60's when they started to think about catching all that vapor. Basically, If you suck gas out, you have to let air in.