I think the post just above mine is one long sentence, I couldn't read it all without making my head spin.
People need to proofread their writing more often.
All RS's have 3 differentials. A LSD can transfer torque side to side, and open diff can't. That's the difference. For example, MY00-01 RS: open front, then center, and LSD in the back. MY98-99 and 02: open front and rear, and of course the "standard" center diff.
Also, the STi's come with front LSD's, don't they?