Torque spec for the pinion shaft nut is 200 pounds, however, there are very specific measurements that need to be taken before changing the pinion shaft seal, and special tools needed to reinstall the pinion shaft seal. The manual specifically says not to hammer the seal into place because damage will occur. The same with the pinion shaft flange plate, it also has to be removed and installed using special tools. Not something that I suggest that you attempt without having the manual in front of you to decide if you want to attempt this without the proper tools. After seeing the information, I would be inclined to leaving this job to someone that has the tools and past experience. If you messed it up, you would be hard pressed to find another differential or repair parts.