Gearbox Oil change

[DanielCS842]

I know there's Alot on here but can't find anything on specifically, I changed the engine and box in my car, as I took driveshafts out I lost alot of oil, I have took Haynes advise and tried to take the Speedo drive off but 1. I can't take the Speedo drive out? No matter what I do, and 2. How do I tell when it is full? Any help would be great, thanks in advance.