The throttle bodies are generally very dirty from the junkyard but are easy to rebuild with a kit from just about any local auto parts store. You’ll need some small Torx bits to disassemble everything. You can send the injectors out to get flow tested and cleaned if necessary. We used WitchHunter Performance. Keep track of how everything goes together. We removed all the gaskets and sensors and cleaned the metal portions of the body with carb cleaner. Sensors can be cleaned with electronics-safe throttle body cleaner. These throttle bodies are marked 4.3L and V-8 and ready to be cleaned up and rebuilt. The spring and diaphragm in the back of the unit regulates the fuel pressure and is critical. If the spring is damaged you must replace it with the correct spring for your application. There are also kits that allow you to modify the pressure regulator so that it’s adjustable. That is desirable if you want to run the system on a modified engine.