I'm on my third f series diff now. Used to punish them every so often and they would just die straight away. Then i got one rebuilt and tightened and this one takes everything i throw at it. But i give it to it sensibly, like no drifting on the dirt and crossing onto tar.
You can get a 4 way spider gear for the centre of the lsd diff from the states but it costs $800 just for the 4way piece. This spreads the load 4 ways instead of two. When you pull about your f series you'll know what i mean.