FC diff in an FD
 

So I've been told countless times I'm going to destroy my diff running a bridge and 83mm turbo...

I did it :)

So what's involved with going with the FC diff? Does the whole diff housing swap in or is it just the carrier? I haven't even bothered to compare the two. A shove in the right direction would be much appreciated.

You will have to use your diff pumpkin (housing) and swap the torsion diff out for the t2 clutch type diff. I recommend letting the a professional do it if you don't know what you are doing.

Make sure you get an S4 TII diff. You'll also need some oem parts, like side oil seals and bearings.

...and I'd recommend letting a professional set the lash.

thanks