Get a 10 bolt truck center You'll also need the two upper and lower long bolts

Pull out your center section knock out the two upper and lower bolts and put the longer ones in

Install the newer center section and your original side gears and put your old axels back in.

Select a dirveshaft angle you want and stitch weld the pillow blocks the stock axel piviots on DONE there are several ratios starting in 55