[dsraven]

google the ranger station for info on the ford 8.8. the explorer diff has an offset center, and I don't know what you need for a width, but some guys cut the long side off, shorten the tube and then use a short side axle on both sides. there is a mustang 8.8 that is centered though, mid 90's? some 8.8's have 3.73 gears, posi and disc brakes. I recommend to grab everything from the donor, including the stabilizer bar and links, the rear section of the driveshaft because the u joint flange is a bit different looking and you may need parts to make it fit, the park brake cables and link where they come together, the brake master cylinder, the brake hose from the frame and the end of the steel line that feeds the hose (you may need the nut off the tube for sizing) etc.
heidts has a good write up on understanding independent front suspension. if you call them they will send it to you. I have a copy but it is too large to post here. you should read up on it and basic mustang II geometry, anti dive angles, bump steer, scrub angles etc. then you will be prepared. set up the suspension and cross member to be level with the frame at the rake angle you like. the lower control arms should be level side to side and front to rear, at ride height. the upper control arms should be level or slightly angled down at the inner end. get it right the first time because that is the base for the rest of the truck. spend the time the first time around.