Complex sentence: Six Flags had previously received many pumps and mechanisms for a rapids ride from Premier Parks, which had previously bought the parts from Opryland USA after previously used on Grizzly River Rampage, a rapids ride, that closed along with Opryland in 1997.
Split into simpler sentences: Six Flags had previously received many pumps and mechanisms for a rapids ride from Premier Parks, which had previously bought the parts from Opryland USA. The parts were from Grizzly River Rampage, a rapids ride, that closed along with Opryland in 1997.