In this article’s the rotors put in. The stock pump is a true Gerotor, where the HKS and many aftermarket pumps tend to be more of a Duocentric rotor design. The RB25 crank collar situation is in fact very common on numerous RB motors, such as the RB20DET and pre-1993 https://nissan-rb26-engine92225.jts-blog.com/27732903/the-definitive-guide-to-rb26det-for-sale