Do I have to change anything other than the drive shafts? My friend keeps breaking them after every week of running.
Drive it like you stole it
No nothing, you can even just swap them as they break, don't have to do all at once.
I replaced all of mine on 2 summits. Mostly because I had the time and bought the erevo set from Dollar Hobbies which has all 4 axles in the pack (great prices also). The only issue I had was stripping out the grub screws that attach the axles to the diff shafts. I discovered that not all hex drivers and hex screw are the same. So now I have 4 different sets of hex drivers and I test each driver to the screws to make sure I have a good fit. The grub screws are pretty cheap I found that I needed 3 different Hex drivers to remove 4 screws. We have not had any broken issues since I replaced the Summit shafts with the mini erevo shafts.
"Better Old and Devious than Young and Exuberant"