Transmission shifts hard from 2 to 3?

I bought this vehicle a few weeks ago. Noticed it shifts hard from 2 to 3. And reverse to drive is funky. Pulled plug from side of transmission to check fluid level. Extremely low. All mechanics I've contacted say to fill, I NEED a pump. There has to be another way. Can I run a hose to the hole to outside the vehicle and use a funnel and gravity? There has got to be a way to fill them without the pump. Thanks for the help.