05 expy rear clunk

[dano]

My 05 Expy has developed a clunk in what sounds like the rear end. The Expy has 105K miles on it. I get the noise when de-celerating. Say I'm driving along 35-40 mph, have to slow down for traffic, apply brakes, let off slightly and clu-clunk. Sometimes also happens when putting along in say a parking lot. Foot on and off brake/ gas pedal, you'll get the clunking. I thought of maybe changing the gear lube back there to see if that would help. Any suggestion would be appriciated,
dano

 

[METALLICA]

I had thesame problem with mine but it's on my front wheel, my mechanic said it was the transfer case.