Dually Rear Lift Help

[ltwnfdc14]

Id like to take out the 2" blocks in the back and install 4" blocks but am having trouble finding the right u bolts. Ive talked to a couple companies that say their lift blocks will work but they do not have the right U bolts. Apparently the Dana 80 dually axle is thicker than the Ford 10.25 in the single wheels. Anyone know who makes longer u bolts for the dually trucks?

[wp6529]

As far as I know, most (heavy) truck spring and brake type shops make their own U bolts and should be able to make U bolts to the dimensions you need.