No, a Pontiac Grand Am master cylinder will not directly fit a Pontiac Grand Prix, even if both cars have ABS. While they're both GM products, the chassis, braking systems, and master cylinder designs differ significantly enough to prevent interchangeability. The bore size, mounting points, and even the reservoir configuration will likely be different.
Trying to force a fit would be unsafe and could lead to brake failure. You must use a master cylinder specifically designed for your year and model of Pontiac Grand Prix. Always check your vehicle's specifications or consult a parts store using your VIN number to ensure you get the correct part.
