Have used 3 different hand pumps...unhappy with all...messy!!!
Have tried gravity feed...works, but slow, messy.
Bought a couple of stainless steel yard sprayers, converted all tubing to reinforced, flexible PVC type (as it does not deteriorate with fluids such as Dexton III), spliced in a shut-off valve and have a very usable delivery system...separate unit for each of the tranny fluids that I use.
Thses rigs have served me well for 10 years.
If I recall, ab posted a similar set-up with pics 4-5 years ago.