#1, Your leak is a pinion seal, and no amount of tightening down bolts will fix that. It's kind of a job to do, you have to drop the driveshaft, remove the pinion flange, pull the seal, replace, and then make sure you get the pinion flange torqued down correctly. Like I said, it's a job, but it's doable in the afternoon if you take it slow and easy.