is the automatic 4.1 differential the same unit with direct fit for the manual rx8's?

I have series I rx8 with 4.4 stock rear differential. I was curious whether automatic 4.1 rear differential is the same LSD unit with the only difference being the rings and pinions..?

also, do we have any other options? like with s2k or 370z differential... I'm asking about a direct fit.. just trying to exhaust all options before I go with 8.8.