tl;dr – our truck is too heavy and the load is improperly presented to the frame. We’re fixing this by replacing the rear frame section with a stronger one, and changing the way the sub-frame presents the payload to the vehicle.
Here’s the frame removal activity. This was done at British 4×4 in Durham, NC. There’s a chain hoist, which made lifting the rear subframe off of the frame an easy task
Lifting the subframe
Frame section removed – we just rolled it out.
Both frame rails broken
Some of the design drawings for the new frame section.
And some images of the new frame pieces coming together at the fabricator…