Seal is a Chicago Rawhide part #7967
20 x 47 x 7 double lip seal.....
You can replace it with the blower still on the engine, but it's a lot easier to remove the entire blower.....
After you get the retainer clip out, you will need to drill two small holes 180° to each other.....
Install two self tapping screws into these holes....
Use a flat blade screwdriver (or other instrument of destruction) to pry the old seal out....
Lube up the inner and outer lips of the new seal and gently press it into the snout.....
You can use a large socket to help get even pressure around the outer edge of the seal.....
If the seal gets cocked to one side, gently remove it and re-seat the spring on the inner lip of the seal....
Be careful, as the inner edge of the retaining ring groove can catch the rubber seal which is a big PITA.....
Now would be a good time to change the oil in the snout....