Datsun Roadster 4:11rear differential pumkin. This was a option which you could purchase from Datsun Competition Department. I ran this is my car all the gears are good but it did wine on acceleration but when you let off it stopped. The patern is off and it is running on the toe of ring gear drive side which means pinion is too shallow. I would check all bearing and set the diff up with the correct shims. This is a open diff not limited slip. SOLD AS IS