By all appearances the 4.1L V6 is a 3.8L V6 with a 1/16'' bigger bore. It looks like one of the few, if not the only, V6 that came with a 4bbl carb (besides the Buick 3.8L turbo).
It was used on 80-84 Buicks, 82 Pontiacs, 81-84 Oldsmobiles, and 81-82 Cadillacs (some sources indicate Cadillac used it in 80-83-84 too, the books don't all agree). Probably it will be found on rwd cars, though some were used in the larger fwd models.
The VIN number on the dash will have a 4 for the engine character for the 4.1L V6. The 5th character for the 80 models or the 8th character for the 81-84 models denotes the engine type.
