S5 rear end into a s4??
 

I found someone selling a s5 GTU 4.30 LSD, and i would looooooooove to put that in my S4 base model, so i could finally have LSD and the gear increase too :)

will it just bolt right in? what other parts might i need?

It will bolt right in. BTW, only the GTUs had the 4.30 LSD.

DO IT ! by the way s4 and s5 rear ends are interchangeable as long as it n/a.
Be sure you test drive the car. after the rear end is installed and notice the faster acc and you go thru the gears faster.

Make certain it's a 4.3 before you complete the purchase.

so if the s4 and s5 diffs are from a turbo II they're not interchangeable?

^

If you are going from turbo to turbo they interchange.

If you are going from n/a to n/a they interchange.

If you are going from n/a to turbo or turbo to n/a, they do not interchange.

If they are a Real 4.30 Rear End then you will not be dissapointed. My GTUs accels way harder than other N/A strictly because of that. the Viscous Rear end definatly is a plus in the corners as well :D