ditch the front rancho's..They suck
..go with stcok rears up front and it will move your front end forward 2inches and will help with some of the drive line angle(thats a cheap way to go).You will also need to build or buy some banana shackles if you use the rears up front.Or invest is some aor springs that can do the same thing.There spendy though.allpro also has them but I don't think theres all that great on trucks.I think they do much better on 4 runners do to weight.Thats just an opinion,and those are like A$$ holes..everybodys got one.
...whats the drive shaft doing.Busting u-joints or coming apart at the shaft?I would think that by going 4in lift and the axle in stock position you would have a pretty sharp angle at extreme flex.So moving the front foward would help.also you can use f-250 shock mounts for longer shocks.