AFAIK there isn't any rear STB's being produced for the B13. I think there were at one time and one of them you had to cut through the sheetmetal by the strut mounts because the bar was in the trunk. Do a search over at the
www.sr20deforum.com, there was a guy who made a nice one that went behind the seat. I plan to make a similar one for mine. I doubt an NX rear STB would work on a Sentra but that's just a guess. You can buy a front one cheap at
www.nopionline.com but call them on the phone because I tried to rder their cheapest one and they were out of stock, but they had others that I didn't ask about.