Having had the overdrive off six times in the last 10 months (don't ask!) filling the gearbox back up again has been a real pain. I'm amazed at how difficult it is.
I intially used a cleaned up rear axle oil squeezy-type container, the ones with the spout, 1/4 a litre at a time took it's time. I then saw a marine-type oil pump in a chandlers and bought that. It took ages as well, but I did have well-good looking biceps afterwards!
My most recent purchase was from Machine Mart who sell what is effectivly a jumbo sized syringe specifically for, wait for it, filling gearboxes!!!. I haven't put this to the test yet but am hopeful it will improve the job. How do the proffesionals do this job?