Hey everybody, i have a e99 F250, 4x4 short bed extended cab, V10, automatic, 189000 miles. While loaded it has a very loud rattle coming from behind the drivers seat, definitely sounds metallic and seems to get worse over bumps while the rattle is present, it only starts at 70ish mph. I have done, ball joints, tie rod ends, sway bar bushings and end links, had the rear driveshaft checked and balanced and removed the front driveshaft all without helping the rattle. It also has a very pronounced snapping sound when going from park to drive or drive to reverse and vise versa. At this point i am leaning towards either transmission or transfer case, but i wanted to check here to see if i was missing anything first. Thanks in advance!

 

If this only happens when you are towing, I would check the hitch and the frame area where the hitch is attached.

 

I should have specified, its loaded whether towing or just a load in the bed.

 

Is the front of the box contacting the cab by any chance?

 

Checked this morning, no contact between cab and bed.

 

Give your rear springs a good look also, are there any broken leaf springs or missing overload spring bushings (on the frame contact points) that can make metal to metal contact with a load on the back of the truck?