I have a '91 F-150 Ext. cab 4x4 lifted 6" suspension and 3" body. The truck right now has a horrible ride on and off road. The suspension is VERY soft and I would almost swear you could put the truck on its top without taking a tire off the ground. It sways that bad. I've already swapped in a 9" rear and am planning on a solid-front axle swap in the near future. Would it be more beneficial to put the body back on the frame and increase the suspension lift to fit the 40's im going to be running soon(if my wal-mart paycheck ever allows it), or just get some really stiff shocks? I don't want to go through a lot of driveshaft mods, but if it would be better overall I'd be willing. Would just like to know what some other people would do/have done in this situation and what came out of it. Thanks

P.S. Will the transfer case out of a 79 F-150(NP208??? I think) replace my Borg Warner 13-56 behind the E4OD...Doubt it, but would like to know incase the BW explodes, implodes or just falls out from underneath the truck.

Body lifts suck in general and can cause the body to shift around on the frame.  No, the older '79 xfer case won't bolt up to your newer fancy tranny, besides not actually bolting up to the tranny, I think the input shaft size and spline count is probably different.

I'm surprised that it rides so poorly (of course it's a ford) my truck rode better after I lifted it.

It's the springs, and/or torsion bars that make the ride, stiffer shocks may or may not help, since shock just help control the rebound of the suspension.