Hello Bruce.
Why would your model need gear oil? Isn't it direct shaft from engine to fan? I can see the self propelled model needing the gear oil since it has a rear gear box as shown:

 

I have downloaded numerous PFD's from Billy goat for Owners manual

(14HP Vanguard engine)

Ummmm Billy don't make the engine

 

I thought that all along as well. No self Propelled, why would there be a gear box. However on checking it says it does, and need gear oil. I am starting to assume there is no gear box, and only straight driver like a push lawn mower. I'm hoping that is right.

 

I owned a Billy Goat blower. Be careful, there was no Low Oil Shutoff on my Vanguard. It didn't end well.

 

I wondered about that, as the manuals I managed to get from sites online didn't tell me much. As soon as I got it home I decided to check the engine over. Nr1 was there wasn't a teaspoon of gasoline in the tank. So I put in about a half tank of fresh 91 octane no ethanol, and treated. I checked the air filter, and it looked good. I checked the oil level and it was on dead bottom of the stick. I will be replacing that soon. I already have the oil. I admit I had a lot of confusion about this engine and the Billy Goat blower. But I am pretty sure I'm okay, we will see in the spring. Of course this unit was used by a man in the business, and his crew wasn't careful with handling it. Orange chute banged up some. I only plan on using it a couple of times each year to clean my own yard. It's business work is over. Sorry about you Van. Thanks for the tip.