Guys - I am now confused. My indy said the best way to add freon (81 300SD) is by weight not pressure. However a forum member Leathermang, who seems to know what he is talking about, reported it should be done by pressure and mentioned a part of the FSM.

Is my indy just wrong - and have I been doing it wrong all these years by topping it off when I see bubbles in the sight glass?