i think that the lsd that comes stock with a wrx is a front to rear lsd? that control slippage between the front and rear tires, not the left and right side

what i would be after would be a front lsd to control the 2 front tires

All Subaru AWD transmissions include a center LSD of varying type. WRXs have a rear LSD which is the same as the one on '00-'01 RSs, just a different ratio.

ah ok, so on my 04 rs, i could just yank out the rear diff and throw in a wrx or 00-01rs diff and presto?

No, you would need an RS diff unless you wanted to swap the ring and pinion from a WRX diff.

i stopped by the subaru recyclers on Sunrise and they quoted me 275 for an 00-01 rs rear differential