So I noticed the other day while picking up the kids, I was parked on a incline and when I went from Park to Reverse if was followed by a loud clank from under my truck('05 2500 Hemi 4x4). I put it back in park and took my foot off the brake pedallet it roll back and put it back in reverse and again a loud clank, any ideas?

 

Sounds like a u-joint.

 

Could be a u joint. Mine will do it every so often as when i put it in D it slams into gear. It did it for a while at some point and i check and double checked everything and then it went away and I havent heard it since

 

I just had my rear u-joint replaced less than 1000 miles ago. Tonight I had a check engine light and pulled a P0700 code.

 

My 2008 does it to,im goina check u joints sat to,went to dodge and the put a valve in the tranny so it doesn't clunk when in drive,that was 2yrs ago.It does it every once in a while now.Just make sure Ur stopped when shifting. J

 

Oh I am stopped, I am going from Park to Reverse.

 

It is because you had 5500lbs of weight resting on a small park pin in the transmission. It pops when you take it out of park, you are releasing a whole lot of pressure off of the pin. I would highly recommend always using the parking brake. Especially when on an incline.