* TH125C: This was a common three-speed automatic transmission.
* 700R4: This was a four-speed automatic, generally found in models with V6 engines or higher-performance options.
To know for sure which automatic transmission is in a *specific* 1985 S10, you need to check the vehicle's identification number (VIN) or the information plate located under the hood or on the driver's side doorjamb. The information on the plate will usually specify the transmission type.