That item is a BPT valve (back pressure transducer). It blocks the vacuum to the EGR valve until there is some pressure in the exhaust system. On some of the early cars with this device they would come unsoldered or detached somehow. Nissan had a recall where they put this brace/bracket to hold the tube against the body. If for some reason you have no tube running up to the transducer from the exhaust or have one of the defective ones have no worries. All that’s happening is that your EGR isn't working. Not good for emissions but unless you have to smog the car or are environmentally conscience your car really won’t care.

See post #18. The actual question that this thread is based on is answered in post #21.

Yea I didn't see the second page

That item is a BPT valve (backpressure transducer). It blocks the vacuum to the EGR valve until there is some pressure in the exhaust system. On some of the early cars with this device they would come unsoldered or detached somehow. Nissan had a recall where they put this brace/bracket to hold the tube against the body. If for some reason you have no tube running up to the transducer from the exhaust or have one of the defective ones have no worries. All that’s happening is that your EGR isn't working. Not good for emissions but unless you have to smog the car or are environmentally conscience your car really won’t care. Some early Fed 280Zs didn't have the EGR and no early car had the BPTD.

The device on the left is the AC idle up. I don't believe I ever saw any Z with a converter that didn't have the floor light. Some of the early 280s had a Catalyst light too. Damn thing came on when a sensor got to a certain temp and tripped a relay. Actually all the early catalytic models had the cat light. Used to have to reset the damn things on brand new cars off the trucks. The guys driving the cars off the boat would start a line of cars and leave em running on the choke while they drove the cars off. On the carburetor cars the fast idle wouldn't shut off by itself in those days and it overheated the cat.

I have a '77 280Z and am replacing all the rotted/broken/missing vacuum lines, but having some confusion regarding a couple:

vacuum lines (2) on BPT? (one goes to EGR, where does the other go?)
vacuum line (2) on THERMAL VACUUM VALVE? (two plastic vacuum lines on end of this were broken off and I don't know where the lines should go)
It also seems that I'm missing some "one-way valves" that should be spliced into some of the vacuum lines...how important are these, where can I get them and where are they needed?
Thanks for the help.
Mark