I don't run any spacers on the inside of the frame on mine, I did however weld a 12 inch piece of 1/8 inch angle iron to the outside of the framerail on both sides where the crossmember bolts up and drilled the holes to 1/2 inch. I used 1/2 inch grade 8 bolts and stover nuts instead of the 3/8 bolts the factory used. I also mark them with torque seal (paint pen) and check them periodically.