Ok - that does not bolt to the frame where I thought it did, and that potentially presents another issue - the need for "crush tubes".
The four "long" bolts in the picture will have to pass through the chassis rail, when you torque them down, they will pull the sides of the rails inwards - it's normal to use what is known as a crush tube to prevent the rails from bending and to help keep the bolts tight - but - if the bolts are that far in on the rails, getting crush tubes in will be a challenge.
Mind you - I don't know where it fits - and as I said earlier, I'm having difficulty visualizing it.