If I remember right, stock 80's/90's F-150 shocks will work in the rear....at 3" of lift I used stock YJ shocks in the front, and stock ZJ shocks in the rear.
Or just go down to National 4WD and spend the money for a new set of the proper ones. For $300 I got a new set for 5" of lift, and that included a steering stabalizer.