The efi trucks don't use a pump, but still do have air injection. See that small tube that goes from the air box over to the plastic ball by the throttle body? This is the intake to the pulse air injection system. It uses exhaust pulses at the manifold to create vacuum to open reed valves and inject air. You will find the air management valve under the intake manifold. I believe the later carbed trucks used pulse air as well.
If you remove the smog pump you will not be able to run a/c as they use the same belt. You would also have to block off the ports in the exhaust manifold. On my 84 I tapped them and installed bolts. Also, I would recommend taping off disconnected connectors for the system, as they would then be hanging around down there, gathering dirt and mud, and can accumulate a suprising amount of battery corrosion too.
Also, if you are thinking of removing the air injection system to gain horsepower, just remember that the air pump only requires something like 2-3 hp.
