This IAC housing is engineered and machined in-house, it fits 1985-1992 TPI and 92-93 LT1, it eliminates the hot engine coolant passage to keep your incoming air cooler to maintain your horsepower aswell as simplifying the lower throttle body area for tight fit applications that need more clearance for the coolant water neck. This housing works great on all stock as well any aftermarket throttle bodies. The passages are all factory so there wont be any idle issues, whistling, or altering of the factory IAC counts