I've already gone through all of the suggested 3-5 threads with most of the info. The previous owner butchered my vac setup and took the vac choke off the carb and converted it over to manual choke. I have since replaced the entire carb with a factory replacement - and now I am left trying to repair the carnage left behind. My truck is a 91 DB51T, Manual Trans, 4x4 (no diff lock), with a 3+2 carb. I seem to be missing an Idle Switch and Vacuum switch. However, I am not sure if my model has one or both of those though, because when looking up replacement parts, they were ID'd for DA51T and DD51T. There are 2 vac ports on the engine that are both currently plugged/unhooked. Where do those connect to? There is a vac line running from the front of the truck to underneath the driver's seat. I am guessing that is for the front diff? Where is does that connect to and is it even needed? I have a mechanical 4x4 lever, and a push button on the dash. When I pull the lever, it lights up. When I push the lever back down the light stays lit until I push the button & then the light goes off. There is currently nothing hooked up to the VSV on the carb #1. There is a screw at #3, that allows that whole piece to move up or down - what does that adjust and how is it tuned?