Small Block Chevy 1985-'92 305/350 Throttle Body 58mm Polished Part #:69706 58MM Throttle Body for 1985-'92 305/350 Throttle Body Style: Multi-port injection, MPI (TPI only, will not fit TBI)Professional Products throttle bodies are precision engineered and many of them are made of aluminum die casting which is the same process used by the original equipment manufactures. Those that are not die cast are made from permanent mold castings, a superior casting process to the sand casting used by all other aftermarket throttle body manufactures making cast throttle bodies. Additionally, not only is the Professional Products Power line of throttle bodies the best quality, they are also the least expensive