I ran a PC680 for about 4 years before it died. I deep cycled it a few times on accident, eventually it didn't hold a charge anymore. I replaced it with a Group 48 or 49, IIRC both are compatible, I chose the smaller of the two. There's two holes you can bolt the OEM clamp down at.
For my PC680 I bought bolt-on SAE terminals from eBay and built my own mount from some steel bar stock and threaded rod. Not pretty but worked great and passed tech. There's $$$ options out there if you want them.
~30lb difference:
