Here's the transmission options. On the left is the GSL-SE, in the middle is the non-turbo FC and on the right is the S4 FC Turbo TII.
Now I've been reading up about swapping FC transmissions into an FB. They all seem to say that you can swap the rear tail section from an GSL-SE transmission unto an FC transmission to make it sit properly.
Well after visualizing and measuring them up against each other I can tell you this is not required. The FC transmission tail-section and shifter location is exactly the same as the GSL-SE transmission. Only difference is the gear ratio's.
You can see that the shifter location on the TII transmission is about an Inch further back then that of the non-turbo FC or FB transmissions. There is an option to shorten the shifter housing on the TII transmission to make it fit as demonstrated by this video... (note: in the video he's talking about modifying it to fit into RX2's and RX3's that use the older SA style transmission which is much shorter. For use in an FB, A TII shifter housing only has to shorted by 1 inch.)
http://www.youtube.com/watch?feature...&v=b_kUr5ZcaH8
Bolting the tail-section of the FB tranny unto a TII transmission is not an option as you can see here from the bolt pattern on the casing.
Not to mention the difference in the output shafts. Turbo's have a thicker one with 23 splines... non turbo's have a thinner one with 22 splines. It would be possible to make a custom driveshaft to match the turbo output shaft with a non turbo driveshaft.
However, modifying the TII shifter housing and making a custom driveshaft isn't something I feel like doing right now. Down the road if I'm making enough power to warrant the need for a TII transmission I will. But for now, a non turbo FC transmission will suffice.