It's about 70 miles below Diamond. Last summer there was current just about four miles above South Cove. So, two very long days. Or three reasonable days. Add a night float to your two days, and you'll be fine. Just make sure someone is watching out for when you exit the Grand Wash Cliffs. or make sure you do it during the day. Pearce Ferry rapid is a little ways after that. It's a great stretch, and hot as hell. The rapids below Diamond are worth it alone. I'll be heading out to the lake in a few weeks, so if there is anything drastically different I'll post about it.