The Turbo 350 (non-lockup style) was built from 1969-1979. Notice how the splines go to the end of the shaft (see Fig. 1 on left). The Turbo 350, non-lockup style, makes a good high performance transmission behind small blocks (not big blocks).
The Turbo 350-C (lockup style) was built from 1980-1986. The Turbo 350-C uses a torque converter with an internal clutch. Notice the machined area and o-ring seal for the converter (see Fig. 2 on left).The Turbo 350-C is not used as a performance transmission. However, the gear train has torrington bearings (rather than thrust washers) and can be installed into the Turbo 350 for performance applications.
DO NOT USE the pump, forward clutch drum with input shaft, valve body, or case from the 350-C when swapping parts to your Turbo 350.
