On my 70 Chevelle, I have a vacuum canister attached to the heater box. There is a larger hose that runs to the fitting on the manifold. There is a smaller hose that goes where?

TIA, Kevin

it goes through the firewall into the heater control valve. If it's not dangling out of the firewall it may have been cut off or pulled back through to the inside. does your car have A/C?

Yes it does have A/C, it doesn't appear to be long enough to go through the firewall, so maybe it was broken off. I'll check tonight.