The oil filter location on a 3.9L Chevy V6 (specifically the 3.9L V6 found in the 1980s and early 1990s, often in S-10 Blazers and Jimmy trucks) is
on the driver's side of the engine block, towards the front. It's typically fairly accessible, though the exact position might vary slightly depending on the year and specific vehicle model. You'll find it nestled amongst other components, likely near the oil pan.
To be absolutely certain, consult a repair manual specific to your vehicle's year and model. A picture in that manual would be invaluable.
