The 1991 Camaro is a third-generation (F-body) car.
No other year Camaros are directly compatible in terms of body parts and major mechanicals. While some parts might share some similarities with other 3rd-gen Camaros (1982-1992), they are *not* interchangeable without modification. Even within the 3rd-gen, there were year-to-year changes.
You'll need to specify *what* parts you're looking for to determine compatibility. For example, some engines or certain electrical components *might* cross over between years, but it's not a guarantee, and often requires some modification. Body panels are almost certainly not interchangeable without extensive work.
