crack from rear end

I have been noticing a cracking sound when i step on the gas... downshift... or hit the brakes hard... it sounds to be coming from somewhere in my driveline... transfer case back... i havent been able to see exactly where its from because i have not jacked up the rear end... i checked all my u joints and they seem to be okay... I had to replace my yoke about 3 months ago... and ever since then i have heard the noise... theres no vibes or anything.. just the loud crack... any ideas on what it is? thanks

Just a stab in the dark, but check you rear shock upper mounts.