six speed rear diff
 

Are all uk sti 6 speed diffs the same 3.545

I believe ratios are the same on all bugs/blobs/hawks, However I know that the backplates and flange the prop shaft bolts too are different from blob to widetrack/hawk, I know this as I had to change the back plate *(no temp sensor in the earlier ones) and the flange for the prop as I have an earlier diff fitted to mine.
I changed my original one for one from an earlier 04 car, but swapped over the flange and backplate to make it fit.

are they 160 ? and the widtrack 180

All newage sti's are 180 diffs

cheers that clears up some issues