The most common answer is that the 1991 S-10 Blazer used a four-speed automatic transmission behind the popular 4.3-liter V6, with a five-speed manual available on certain configurations. The exact unit depended on engine and drivetrain, so checking your specific vehicle is the surest way to know.
Transmission options in the 1991 S-10 Blazer
Below is a concise guide to the two broad transmission categories that GM offered for the year, highlighting the configuration that most owners encountered.
Automatic transmissions
Before listing the options, note that the automatic most commonly paired with the 4.3-liter V6 in the 1991 S-10 Blazer was a four-speed automatic from the 700R4/4L60 family. This transmission was used across many GM light trucks in that era and provided overdrive for better highway cruising. It was typically found in both 2WD and 4WD Blazers with the V6 engine.
- 4-speed automatic in the 700R4/4L60 family, most often paired with the 4.3L V6 in the Blazer’s range of configurations.
Concluding paragraph: The four-speed automatic was the standard choice for most 1991 S-10 Blazers with the V6, offering reliability and widespread parts availability.
Manual transmissions
Before listing, keep in mind that a five-speed manual was offered on select 1991 S-10 Blazer configurations, typically with smaller-displacement engines or specific trim packages. Manuals were less common than automatics but existed for enthusiasts or certain market specs.
- 5-speed manual transmission available on select configurations (often with the 2.5L inline-four or other specific setups).
Concluding paragraph: Manual transmissions were not universal in the 1991 S-10 Blazer, but they were a factory option on certain configurations, particularly those favoring a lighter setup or manual control.
How to identify the exact transmission in your Blazer
If you want to confirm the precise unit in your truck, use these steps to verify the transmission type.
- Check the transmission case for a model code stamped on the side of the bellhousing or near the pan; GM codes can indicate whether you have a 700R4/4L60-family automatic or a manual transmission.
- Look at the shifter pattern and markings: an automatic will show PRNDL with overdrive, while a manual will have a traditional gear pattern with reverse and a clutch pedal.
- Consult the vehicle’s build sheet, window sticker, or VIN-based factory code to confirm the original transmission specification for your exact vehicle.
Concluding paragraph: A quick inspection or a VIN/build sheet lookup will usually confirm the exact transmission in your 1991 S-10 Blazer.
Summary
In 1991, the Chevrolet S-10 Blazer predominantly used a four-speed automatic transmission in the 700R4/4L60 family behind the common 4.3L V6, with a five-speed manual option available on select configurations (often tied to the 2.5L I4). The best way to know your specific truck’s setup is to verify via the build sheet, VIN, or by inspecting the transmission code on the case. Understanding the exact unit is useful for maintenance, parts compatibility, and future swaps.