I can't seem to find what I'm looking for.

Anyone using a short pinion diff. in an FC?

All my searches keep coming up with lengthening short pinions to fit the FC case.

It seems like using the short pinion diff (namely Sportage) with a longer/custom front diff mount and drive shaft would be cheaper then lengthening an FB pinion longer.

Just wondering.

 

Most people who are doing this are restricted by racing rules that say that you have to keep the stock case, so they've got to lenghten the shaft. I'd always figured a Miata 7" diff would be the perfect swap, they use the same rear housing (different bushings) which makes things easier. Then, as you said, just a custom front mount and longer driveshaft. It might not save any money for a single gear, but if you want multiple diffs for different track setups, I have to believe that it'll be cheaper than modifying each and every pinion.

 

im using a b1600/b2000 diff head in my s4 fc3s(factory turbo model) which required a new front mount and a longer driveshaft,this gave me a ratio of 4.99/1 which has been a big improvement as im running a 13b brigdeport non turbo.it was a pain to setup as i modifyed i s5 lsd centre to fit into it,but otherwise straight forward and the cheapest way to get a better ratio!