What 3" lift do you have now? More than likely, you already have 4" of lift. To add more life, new coils and longer shocks are the basics of what you'll need but at that sky high height, there's a lot more you should have to correct your suspension and steering geometry. Are they "necessary"? No. But, they are what I would want for a better ride and handling.
I have a 4inch and I would suggest a front driveshaft. It is not necessary right off the back but my angle on the transfer case side is pretty bad and I expect it to fail.