i purchased an rb25 to swap into a 91 300zx it is in the car. the car runs and drives, but i noticed some different badging on the motor specifically a reinik valley cover when looking this up i stumbled up the casting number matching a 280mr apparently there are only 13 accounted for from the original 20 so they took rb25 and bored them to a 2.8 with forged internals. I was just wondering if anyone had any further info on this thanks