I recently repeated this trip. I had a lot of fun, saw a lot of animals, and
made a discovery. During my last trip, I ran into a guy upstream of Bell
Crossing. He asked me if I had seen the cliff dwelling. I must have walked right
past it. Even though I was keeping my eyes peeled for it, I almost missed it on
this trip as well. I happened to find it through pure luck. I took a break atop
a sandstone ledge above the creek, and found a
grinding hole 
in the rock. I realized it must be close, so I looked up and there was the
cliff dwelling.
This thing is really easy to miss, so here are a few clues. It's on the north
wall of the canyon, overlooking a red sandstone ledge above a series of small
waterfalls. It's small and somewhat obscure, so you might not be able to see it
if you are standing in the creek. I didn't see it until I was on the ledge. If
you are coming downstream from Waldroup Canyon, then the cliff dwelling is just
past the third mandatory swim after the
logjam. If you
are coming upstream from Bell Crossing, then it is just past the swimming hole
beneath the big balanced rock. I don't know exactly how far the cliff dwelling
is from Bell Crossing. The canyon twists and turns so much that mileage become
totally irrelevant. However, the dwelling was about a 4 hour walk from the
crossing. A person could easily go for a three-day trip, camping at Bell
Crossing and using the middle day to walk up to the cliff dwelling. A really
determined/maniacal person could probably do it in one day if they started on
the Bell Trail before sunrise.