I don't think all 180sx's have 4.36... In fact most were the 4.08 that's the same as the USDM cars got. Crack the case open and get the numbers off the ring gear to prove it. If it is the 4.36 diff it's worth the asking price. If not, ehh. Not so much.

5 bolt, 4.08 (they call it 4.1, but they're just rounding... I believe)

JDM Nissan 240SX S13 Rear Differential VLSD 4.1 LSD ABS:eBay Motors (item 150393633950 end time Dec-07-09 19:01:34 PST)

more info here:

http://zilvia.net/f/tech-talk/83246-...ive-ratio.html