I have a 2000 Z71 and it has clunked since it was new.

 

there is a normal clunk from the play in the drivetrain. and then there is a clunk that means your tranny is on the way out.
i had it on my truck and ignored it kinda and figrued if it goes it goes. it was when the tranny started slippin when i floored it that i ripped it out and rebuilt it, but there was 260000 k on it

 

thanks guys, I told my dealer I'd be looking else where when it came time to puchase again . The answer normal just doesn't cut it.

 

Ive had a 99 Z71 and now a 04 2500hd and the both make a clunking sound when shifting from park if on a slight incline. If apply parking brake before putting in park it doesnt do it. This is the only clunking noise either of mine have made while shifting.