My name says it all. I thought the differential plate was leaking so I got a gasket went under and then noticed it was coming from the seal. The car is a 72 cutlass 350 that has been sitting since the reagen administration. I know its not positraction but that's about it. How do I determine if its a c clip or not, if I get the bearing and seal would a newbie be able to do. Can I just do the seal and not the bearing? Do I have to take the whole axle off. I know some of these answers might be in past post but I'm. On my phone and the connection sucks.

 

Pull one of the rear wheel off and that brake drum. If there are holes in the axle flange that give you access to the backing plate bolts then it's a bolt in housing, if not it's c-clips.

You can do the seal without dropping the rear end. You'll need to pull the driveshaft and then the pinion yoke to get it out.

Now if you're talking about an axle seal then it's a different ballgame. The bolt in axles are pretty straightforward, but you may need an axe puller that can be rented/borrowed from the local parts store.

The C-clip rear will require you to pull the diff cover and thus drain the fluid, unbolt the cross shaft pin and slide it out. Then you can push the axle shafts in to release the C-clips one at a time and then pull the axles out of the housing. I'd do both of these just to make sure you don't have to do it again when the other side decides to start leaking in a week.

 

My terminology might be off. The leak is from where the driveshaft enters the rear axle.

 

That's the pinion seal.

 

Better left to somone with a impact gun and a torque wrench that has done it before.
Pick-up the part, and call around to your local shops for prices, mentioning you've got the pinion seal.
Less than an hour, with the proper tools and experience, and don't be surprised if they tell you you need u-joints, too!