Clunk coming from rear?

[muthstryker]

Hey guys, took my truck out of the garage yesterday for a ride around the block real quick and when I brake, there is a loud clunk in the rear. I can feel it too. I cant figure it out... The truck will be alinged this friday and dont plan on driving it untill it is aligned but what could this be?

Is it possible my pinion angle is off causing the drive shaft to clunk? Or?...

The correct drop shocks for the rear are on the way do you think its maybe a shock thing and I should see what happens when I replace the stock shocks with the lowered shocks?