Jims Fork Filling Tool #740. Hook a Mity Vac to it pump it up to 23-25 pounds of pressure, turn the lever after filling the container with the correct amount of fork oil, and fill the fork through the drain holes. It is sold on a couple of Harley sites and the main selling point is you do not have to pull all of upper tin work on Glide and other HD forks like my Servi Car to get to the fork caps. It is also a long process if you fill from the top since the early fork tubes have to be filled very slowly. The manual suggests making a contraction with a funnel and rubber stopper and let it hang overnight, seriously.
This damn thing sells for ridiculous money but I found this one used on Facebook Market Place and of course the seller said he had used it and it worked great but he had sold his bike and just wanted it gone. It has been too cold to give it a try, but will post the results when I do. Yes I am a sucker for weird tools you only use occasionally, the ones you can never remember where you put them when the time comes for use.........