lets say it is the u-joints, what size are they? it looks like the zone has two different sizes...
In the thread where I was trying to get help on my differential problem (before I knew it was a diff problem) people were suggesting the drive shaft u-joints. I was told by one person to drive around with the vehicle, then feel the shaft u-joints. If they were super hot, then that was probably the problem. Mine weren't hot. Warm... a little bit, but not even hot to the touch. You migh lift rear on some stands, have someone stand behind the vehicle, put it in gear and let the rear wheels spin a bit and see if they can still hear or pinpoint the noise.
I'm no expert on this, but I seriously don't believe a u-joint would only make noise on deceleration. It should make noise while it spins, period. I have read on many a thread that a faulty differential problem will cause a noise on acceleration or deceleration only, because the stress is being put on different sides of the gears.