There should be a separate "can" for the flashers from the signals. I can't say for a '67, but the 65's didn't have it in the fusebox, it was under the dash by the column somewhere.
67's are on the back of the instrument panel. There are two plastic 'cups' that hold the flashers. Most of the replacements at the store are too big to fit into the cup, so be careful.
Behind the gauges - mine has a metal clip attached to one of the steel supports back there, but I don't use it because a) it doesn't stay in there and b) the metal clip amplifies the clicking of the relay. So it just dangles but works fine.