14" out of the middle, about 6" off the end, move the rear most crossmember first. 16 gal gas tank, new parking brake cables, new rear brake line (from a junction under the cab to the rear axle), shorten driveshaft. Thats pretty much it. Here is a write up with a little more detail.
http://www.73-87.com/7387garage/chas...lwb_to_swb.htm
Thanks,
Paul