My son just bought a 1985 C20 with 6.2l/th400. The engine runs but smokes badly (suspect inj pump). He got a deal on a 6.2l out of an airport tug with 16k on the odometer. There was another owner who bought the engine out of the tug at the wrecking yard and drove it for a year. The engine leaked badly so he resealed the entire engine, put head studs in, an upgraded inj pump, new balancer etc. He had also purchased a new Banks turbo kit that came with the engine purchase. All looks good except we're missing the "top hat" for the Banks intake, anyone have one sitting around that they'd be will to sell? We noticed that the current engine in the truck as an assembly on the passenger side of the inj pump with a few vac lines coming out of it. The tug pull out engine does not have this component. What is it? Something to do with the vac modulator on the 400 trans I'm guessing? Can this part just be swapped from the old engine to the tug engine? And there is a vac line going from it down the th400 dip stick to the trans? Also, there is a sensor type unit on the rear inside of the cylinder head. On the tug engine, this unit is on the driver head with a 4 lead plug assembly and on the original engine its on the passenger head with only two wires. What is this for? For performance, is he better off staying with the non egr 6.2l manifold and buying the Banks top hat or just switching to a F code 6.5l manifold.