Here's what I did on my 46. These widths fit the original cross sill holes. 7 1/8" 5 1/2" 5 1/2" 9 1/8" 5 1/2" 5 1/2" 7 1/8". Someone on here sent or posted me these so you can thank someone else...lol Thread on my bed here. Mar-K has a bed assembly guide that contains information and pictures to aid in the assembly. Hope this helps. Have fun and good luck
Dan