The upper spring flanges have to be changed to the quad style, and the lower mount for the front shock has to be installed where the blank spacer is bolted to the front of the axle on each side. The flanges are riveted to the frame and the rivets must be ground off and punched out. Since the brake lines pass thru them, you may have to get the truck towed to a dealer to have the 4WABS bled - check into this before you go too far. Use grade 8 American or material class 8.8, 9.8, 10.8 metric bolts to reattach them with crimped or other locking nuts. The lower mounts are captive between the radius arm and the axle housing, and you have to pull the spring perch to get to the stud on top. As I recall, the stud on top and the bolt on bottom require a 1 1/16" wrench with a LONG handle - lotsa torque. Use plenty of liquid wrench to get them off, and anti-sieze lube when you put them back.
As much work as this is (and it IS a lot of work), I can say that if I had to do it again, I would. The improvement in ride quality and handling easily justifies the effort. (But I don't have 4WABS, so I didn't have to check into that.) I'm surprised an XLT didn't come with quads.
BTW In case you hadn't seen them, there are a bunch of pics of my truck online. Go to www.wephotos.com
and put "steve" in the "Email/Nickname" field, then select "My 83 Bronco" from the albumn list. Clicking on a pic will enlarge it and show the caption, and you can move thru the pics with < & > buttons or a pulldown list. The finished quad shock install is titled "If the Bronco's rockin'..." .
83 Custom w/95 4.9L EFI, 78 NP435, 83 NP208, 83 D44IFS 3.07, 87 Ford 8.8ABS 3.08, Michelin LTX AT 31x10.50R15