shortening a rear axle?

my bare 8.75 housing is 52.5"...books show 52 5/8...so people run 10" rims with 7.5 backspace on this combo...so if u want 5.5 back space i think u would want your bare housing to be around 48.5"...like said above, if u know what wheels u want, get them and tires first and go from there...make sure u find out the proper offset for the dana and see if u have enough axle tube on the long side to get it right :)