I am hearing that the us s1 3rd-4th parts will not work on the jdm s1 transmission. I hear the main problem is getting the synchro sleeve. I want to get carbon coated synchros if possible. I want to replace all the synchros while I'm at it. Maybe rebuild kit also. Does 3rd gear or the firks come up damaged also. I put lsd in it 4 monthes ago and everything looked good. A few trips of quick shifting down the track took care of it.(skunk2 shifter). I just shift 1-2-4-5 now. 3rd Grinds sometimes if revs are only 1,000. Yes I have the 3rd-4th shift grind blues!!!!!!!