Missing vent line..70 Z28..NA9 emission control

[TDW]

This is on my Los built, Ca sold 70 Z28 with NA9.
There is supposed to be a vent line, steel, that runs with the brake line on the drivers side. The steel line is supposed to be hooked to the charcol cannister with a rubber hose and supposed to be hooked to the seperator assem. with a short rubber hose.
There is no evidence that the line was ever there. The seperator is there, with the original 6" hose that is supposed to hook to the steel line and it has the original pink hose clamp. The pink clamp is about 1" onto the hose, it looks like it has never been moved. It looks like there was never a steel line inserted into the hose. All of the brake line frame clamps are for a single line, whereas the Assem. manual shows there should be 2 lines, the brake line and the vent line, attached to the frame with a clamp designed to hold 2 lines.
The factory undercoating is still on the frame. The bolts holding the clamps appear to be original, never removed. The assem manual also shows there should be a double clamp on the firewall where the brake line and the vent come out near the booster. There is no hole for this clamp in the firewall.
The original charcol cannister is there, with the 4 nipples for the NA9 system. The build sheet calls for NA9.
My first thought was someone removed the steel line, but after seeing the 6" hose, no hole in the firewall, and the undercoatig looking original, the single line frame clamps, I don't know. My second thought was the line was removed, the clamps replaced with the correct single ones, and the car had aftermarket undercoating applied. Any thoughts on this? Thanks.

[Mr70]

I've seen a few vehicles like that.
There was a Van Nuys-November built & CA. sold,1970 L-78 Chevelle w/NA-9,echoing your vehicles description nearly verbatim.
It was a new RPO for 1970,so I just chalked it up as early assembly work error.They probably didn't quality check this RPO too well in the beginning.

[TDW]

I had that thought too, but I can't figure out what they would have done with the rubber hose from the cannister, except let it hang under the master cyld.

PS...That makes me feel a little better that you have seen this before!