I find the easiest way to get the fluid in, cos it ain't easy, is to buy a garden spraying thing, put the ATF in it, take the end off the spray end then pump it up and use it to fill the box with.
This sort of thing, or a bit bigger if you feel the need
https://www.zoro.co.uk/shop/hand-to...MI-YHN5o-L7wIVy4FQBh27yg4-EAQYBSABEgLu4vD_BwE
This sort of thing, or a bit bigger if you feel the need
https://www.zoro.co.uk/shop/hand-to...MI-YHN5o-L7wIVy4FQBh27yg4-EAQYBSABEgLu4vD_BwE