* TH350 (3-speed automatic): This was a very popular choice.
* TH400 (3-speed automatic): A heavier-duty 3-speed automatic, often found in higher-performance or heavier-duty trucks.
* SM465 (4-speed manual): A durable 4-speed manual transmission.
* SM465 (5-speed manual): Less common but possible, depending on options.
To know for sure what transmission is in a *specific* 1983 Silverado, you'd need to check the vehicle's identification number (VIN) or look at the transmission itself (usually stamped with identification numbers). The owner's manual (if available) would also list the transmission type.