Sounds like "clank-uh, clank-uh, clank-uh" to me.
U-joints get my vote. Just what you need, spend $1,400 for a one-piece carbon fiber drive shaft and your noise will be gone.
Mods: Ridetech coilovers, prothane bushings, braided brake lines, Pfadt ZL1 style sways, Hawk ceramic pads, Spohn trailing arms, Kooks 1 7/8 LT's, HF cats, Magnaflow 3" cat-back, MBRP rec tips, Cold Air Inductions black CAI, MGW short-throw shifter w/retro shift ball, Showstopper Engine Bling, Forgeline MD3P's 9.5 & 11", Conti DWS 275's & 315's. JDP harness and DRL's. Seibon carbon fiber GFX, Anvil carbon fiber rear spoiler. Oracle ghosted LED side marker lights.
Proud previous owner of: 1968 327 Camaro, 1972 Camaro SS 350, 1978 Z28, 1979 Z28. 2010 SS is My 5th Camaro