Smooth transmission performance is a vital part of drivability. All the power and rumbling horsepower in the world is useless if there is a tired and worn transmission delivering gear commands to the differential. High-mileage trucks with several years of hauling and road time under their belts usually warrant transmission attention. One of the classic transmissions found in several older GM offerings is the Turbo 350 three-speed transmission. The Turbo 350 is an economical alternative to more current 700-R4, 4L60E, and 4L80E overdrive units, which can put a hefty strain on the wallet when it comes time to rebuild or replace.
Recently, we noticed that the original Turbo 350 transmission in our '85 Chevy C10 project truck was beginning to slip and leak an excessive amount of fluid out of the front seal. Since we planned on driving this truck considerably after its first show season tour, a fresh replacement gearbox was a must for worry-free driving. The transmission specialists at SW Performance Transmissions in Huntington Beach, California, answered our shifting prayers with a freshly rebuilt Turbo 350 to slide under our C10. Before hoisting the replacement SW Transmission in place, we decided to take an inside tour with owner Steve White of this classic transmission and show what makes it tick.