[WKB]

Sambo,

You can use the S15 diff in the GTST K frame by changing the back cover and swapping the drive shafts over. The holes in the front of the diff will line up with the holes in the K frame, but will need a plug in them as the holes are bigger than the original diff. If you are going to fit one do it before you get the tailshaft made as the S15 diff has a ABS speed sensor behind the the drive flange which makes it longer than the standard GTST diff. The S15 ratio is 3.69 to 1 which is a good replacement for the GTST diff if you want a higher diff ratio. S15 diffs come up a ebay every now and then. I bought one for $250 recently.

Warren