It's not the only option. The parts store showed a Bosch ($$$) Valeo ($$x$$) and their Carquest alternator with lifetime warranty. But, the Bosch and Carquest came with the 6 rib pulley. We pulled the 6 rib off and put my 8 rib on but it protruded more than normal. That was enough for me to go for a stock alternator to be sure offset for the serpentine belt was correct.

Les