[TrailLeadr]

I think he's trying to determine if his engine has EGR, or an air pump.
As far as I know they stopped putting air pumps on these engines when OBD II came along (1996), as EGR was easier to manage with OBD II, and more efficient. But I could be wrong.

We would need to know more about your rig, if you can provide that info.

 

[TrailLeadr]

I looked back in his posts and its a 99' Z71 5.3l, wouldn't that be 5.7l. I thought 5.3l didn't come out till later? 99 would definitely be EGR managed by OBDII, correct?

The 5.3L was offered in '99.

My book doesn't give indications of a cut-off where air pumps were no longer used. It's possible they were still included, but I'd guess that they were more than likely used in conjunction with EGR, not as a substitute by 1999.

I think we need a better explanation of what he means by A.I.R.