You want to get the straight story, so call the California Air Resource Board. They are very helpful in telling you what you will need to be SMOG legal.
In general you will need the following:
All SMOG equipment from the donor vehicle must be installed on your truck. The parts may vary from year to year and model to model. Obviously if you have a donor car than you can just take everything you need off of it. If you have just a motor than you will run into issues with the referree.
Y pipe and catylitic converters.
Air pump if equiped
Exhaust manifolds or CARB approved headers
Oxygen sensors
Maf or Map sensor
Parts of intake
Computer
EGR valve and pipes
AIT sensor
ECT sensor
TP sensor
EVAP canister purge solenoid and valve
Charcoal canister
Knock sensor
DLC Data Link Connector
MIL light Malfunction Indicator Light
Some referree's will have a cow about the routing of your exhaust which can't be duplicated like the donor vehicle.
When using a 4l60 tranny make sure it came out of a 2 wheel drive vehicle or else you will need to change the out put shaft.
In some applications you can get a harness as long as it has all the smog connections on it, so be careful. You can also get the donor harness and send it out to get reworked for you. On some computers you will need to have things like the Anti Theft Programming taken out or you will not be able to start the vehicle. If the donor vehicle had a VATS theft system in you can just buy a module to over ride it, but if it had a Pass Lock system then it needs to be programmed out. You may also need to have the fuel level sensor DTC removed along with the Fuel tank pressure sensor DTC. Most of the above refers to a SFI engine and not a TBI motor. The TBI would be less complicated.
