some companies that sell good stuff are:
clayton offroad (sells currie products)
i would recommend that you make them adjustable. this way when you lift it and start changing things you will be able to dial in the pinion angle and axle placement. i have used the ballistic fab weld on flex joints. they are really nice.
'98 ZJ on 37s and tons
'02 Chevy 2500HD 8.1