Is anyone familiar with "secondary air injection"? Is this simply an extra belt driven air pump, or is it more complicated than that?

 

more complicated than that,
if your swaping engines you can use your heads on the 99 block as long as it came from a DII. If you swap heads you will also be starting off with new head gaskets.

 

Secondary air is the biggest PIA POS system. Adds lots of pain to otherwise simple jobs.

 

Is by-passing the system an option? Couple caps and plugs/or does it have an impact on other electrical systems.

 

you need to keep it, is there an issue with it?

 

So, first, what is wrong with your 02?
How many miles on the 99?
You will find, depending on the conditions of the 02 heads and the overall wear on th 99 block, you will have extra work involved.
How mechanical are you or are you having a shop do the work?

 

Haven't bought the '02 yet but it alledgedly "has a bad valve and may need a sleeve" is what the owners mechanic told him. My '99 has a bad transmission, 107k miles, and the body is being used on another project. I'm trying to either sell the '99 drivetrain and/or possibly use the motor to fix another one, then sell it. My '99 does not have secondary, but according to the vin, the '02 prospect does.