What transmission is in a 87 S10?
The 1987 Chevrolet S-10 offered two main transmission choices: a five-speed manual or a three-speed automatic, with the automatic being the more common option across most engines. The exact setup depended on the engine and trim level on the truck you’re looking at.
In this article, we break down the available transmissions for the 1987 S-10, explain how to tell which one your particular truck has, and offer guidance on identifying parts and compatibility for maintenance or restoration. The information reflects typical factory configurations from that year and can help buyers, owners, and restorers confirm which transmission is installed.
Transmission options for the 1987 S-10
Here are the primary transmission configurations you would encounter on a 1987 S-10, depending on engine and trim:
- Five-speed manual transmission — commonly paired with the 2.5L inline-four engine and available on select trims; used when a manual shift option was specified by the buyer.
- Three-speed automatic transmission (TH125C) — the most widely installed automatic across many engine configurations, including the 2.5L and 2.8L V6, and found on most standard cab models or optional-equipped trucks.
In addition, four-wheel-drive versions of the 87 S-10 used the same two transmission options, with the appropriate transfer-case setup to deliver four-wheel drive. The core choice—manual five-speed or automatic three-speed—remained the central determinant for most buyers and restorers.
How to identify which transmission you have
Use these practical checks to determine the exact transmission in your 1987 S-10:
- Inspect the gear shifter: a floor-mounted stick with gear indicators showing five forward positions typically indicates a manual transmission; a lever labeled Park/Reverse/Neutral/Drive (plus L or 2/1 on some autos) indicates an automatic.
- Look for transmission casing markings: many units carry a casting code or tag on the bellhousing or side of the case that can be cross-referenced with GM transmission codes to confirm TH125C vs. manual.
- Check the transmission pan and bolt pattern: automatic transmissions generally have a distinctive pan shape and multiple bolts around the perimeter; manual transmissions have a different bellhousing-to-case configuration and fewer external oil plugs on the pan.
- Review the build sheet or glovebox/RPO codes: the option codes listed for your vehicle (such as those indicating manual or automatic transmission) can confirm the original spec.
- Consult a service manual or serial/VIN-based lookup: if you’re unsure, a dealer or mechanic can decode the vehicle’s original equipment based on its VIN and production date.
Knowing the exact transmission is crucial for buying replacement parts, performing repairs, or planning a restoration that stays true to the original configuration.
Summary
For a 1987 S-10, the two main transmission choices were a five-speed manual and a three-speed automatic TH125C. The manual was largely associated with the base four-cylinder setup, while the automatic was prevalent across most configurations. Identification involves checking the gear selector, looking for casting or tag codes, and consulting the build sheet or VIN-based resources. With these steps, you can confirm which transmission your S-10 has and source the correct parts or plan maintenance accordingly.
