Is this a leaking pinion seal? Any tips on replacing it? Ford 9"

I have a 1970 Mercury Cougar 9" differential in my truck. It started dripping earlier this year. I thought it needed a gasket. I went out this morning to a puddle under the rear end. It looks like the pinion seal is leaking.



I found this video on replacing the seal. Does this seem right? Anything you'd like to add?

http://www.youtube.com/watch?v=pCy0Xdz6SNI

While I'm thinking about it, the truck sat for a couple years. I recently took it out around the block and a couple days later find the puddle. Could this have contributed to the leak?

 

Tough crowd. Maybe you night guys will have a thought.

 

I just changed the seal and yoke on my 9" and what i would do is mark the nut and pinion and write down how many threads are showing before you take it apart, after you take apart and replace seal re-install and tighten so marks line up and same number of threads show. giving it a little extra doesn't hurt. I can say the 3/4" drive electric impact i used was a great help, had adaptor to use 1/2" drive socket that was 1 1/16" or 27mm.

 

If the seal surface on the yoke is worn or grooved you will need a SPEEDI-SLEEVE in addition to a fresh seal.

 

check the vent first,make sure its not stopped up with dirt daubers.