I know people like to swap the two-piece for a single, but its a good idea to consider why you'd want to do it. Using a two-piece you can get your truck lower while maintaining the correct pininon angle and limiting the size of the driveshaft tunnel.
I know one guy who thinks a performance truck must have a one piece drive shaft. I disagree.
Looking under modern big trucks you often see two-piece drive shafts. If one of those can stand the stress applied to start out 80,000 pounds and more, then it seems the issue is getting the right parts in place and set up correctly.
You don't say why you want to change. What are you trying to accomplish?
