Are we sure they used U bolts?
All the CMP I have seen had long bolts going through thick plates to both the bottom of the frame and on top under the box???
If U bolts are used they would need to be installed up side down...U pointing up... and a 1/4 inch on top. They will not fit otherwise in the right space un
de the frame. Very critical dimensions on the length of the U bolt as the top threaded end must fit the exact thickness of the frame plus the wooden spacer und the box and still have enough length to instal the top plate, lock washer and long U bolt nuts....if the U bolt is too long, once the boxes sits on the frame you will not be able to fit the nut.......
I have fabricated long bolts with plates at both end as that is the only way I have seen them installed......... Could it be that all the trucks I have seen had the boxes removed and reinstalled with bolts and plates sometimes in their career??
I have seen wooden blocks to stiffen the frames..... made of thick hard wood and groved on the inside portion to allow the inside bolt to hold it in place.......
Comments!!!