how interchangeable are fc rear diffs? could you mix different series? or is it too much hassle.

 

The diffs are bolt in, but the driveshaft needs to be custom when using a different trans vs diff. (tii trans to n/a diff, or n/a trans to tii diff)

And you need to use the axles that match the diff. (tii axles on tii diff, n/a axles on n/a diff)

 

so as long as its all tii it's fine? different series doesn't matter?

 

Different series doesn't matter.

As a reference for TII diffs I believe
S4 = Clutch Type LSD
S5 = Viscous Type LSD

 

thanks farberio

 

will the tii diff work with the fd axles?