Where is the number 1 distributor peg on a 1986 Chevy S10?

There's no single "number 1 distributor peg" on a 1986 Chevy S10 distributor in the same way some older engines had a clearly marked number 1 position. The rotor's position relative to the cap is what matters.

To find the correct distributor position, you need to:

1. Identify the number 1 cylinder: This is usually the cylinder closest to the radiator on the passenger side of the engine (V6). Consult your engine's specifications or a repair manual for your specific engine (there were various V6 and 4-cylinder options in 1986 S10s).

2. Find the number 1 spark plug wire: This wire connects to the number 1 spark plug.

3. Align the rotor: With the engine at its number 1 Top Dead Center (TDC) compression stroke, the rotor should be pointing towards the terminal in the distributor cap that corresponds to the number 1 spark plug wire. This is how you set the distributor's position correctly. A timing light and the engine's timing marks will help you verify TDC.

In short, you don't look for a "number 1 peg" but rather use the firing order and the position of the rotor to align the distributor. A repair manual is highly recommended for this procedure; incorrectly installing the distributor can severely damage your engine.