Styles

From the looks of that part number I'd say they're 910 Bluebird.

Sorry, haven't been on in ages, and you've probably already fixed it, but yeah, they are special (from memory) they're an o-ring on a metaltube shaped bit I recall.

Yep, it is fairly common, there are two o-rings in behind the front cover that leak. They're part number 150665E510 and they're about $25 each from you local Nissan dealer. My missus' car is leaking from there, but it's not too bad, so I'm putting it off untill it gets worse, or I get her a new car.