So I have this noise underneath that I'm thinking is the trans cross member but not sure. It sounds like the clack of a Torque wrench when it gets to it's torque setting but louder..bought the truck used with a 6" Fabtech lift. Does it when braking when I'm slowing down to almost a stop and also does it if I go over a big bump slowly like pulling out of my driveway ( little hump day end of driveway). Please help as it driving me crazy. Thanks

 

It might help to have someone open the door or stand on the running board and bounce up and down while you listen and or feel around underneath.
When my truck was clunking it was the sway bar end links but it could be anything in the suspension I guess.

 

Could be sway bar end links. Could be loose shock bolt. Could be any other loose bolt. Give the underside a good look. Could also be the leaf springs. Could be a loose spare tire. See where I'm going with this? Could be a friend playing a prank on you and put a nut on a string in your frame that clanks around at times. I've heard of people doing that before. LOL

 

I suspect it's the transmission cross member. It's got the Fabtech impact struts attached to it and maybe stressing it. I changed the trans mount few weeks ago and it seemed to fix it then it came back