I built a new bed on sawhorses. I duct taped 4x4s to the top of each sawhorse to make them wide enough to hold the bed. To square the bed, you must measure diagonally from left front corner to right rear corner and the other side. Keep adjusting until both measurements are within 1/8" or less. I duct taped 2x4s to the top of each frame rail, this minimizes difficulty of sliding the bed over the frame's rear axle hump. I walked the sawhorses to the back of the bed and lifted the bed onto the frame rail boards. I then pushed the bed forward on the frame rails. I then just picked up each side and pulled the board off the frame. It wasn't five minutes from sawhorses to dropping in the first bolt through bed and frame. All eight bed to frame bolts fell in perfectly thanks to measuring several times to square it up. Crude, but it worked and I'd do it again.
