Big Clunk when taking off?(91 C1500)

Hey you guys Ive got a '91 C1500 that makes a big clunk when your taking off from a red light. It has got something to do with either the rear end or rear suspension but I can't quite figure it out. If anybody has any ideas please let me know I would appreciate it.

Thanks

My 92 does the same thing. It was my dads before I got it and he bought it new. Its been doing that since birth. The dealer says its the splines in the transmission/drive shaft connection. Pull the spline shaft and grease them and it goes away. The funny thing is that it keeps coming back.

Actually, I believe it to be the rear differential, read this post.
http://www.automotiveforums.com/vbulletin/showthread.php?t=713022

Yeah I'm gonna check that out and see if maybe that will do the trick otherwise I'm gonna open up the differential and see what going on. Thanks fro the reply.

Another thought is it could be the rear brakes releasing when you take off.

Thats another thought because I've actually had my brakes pulsating for quite some time so maybe i'll check out all the brakes and see if anything is out of place or something.