I use the one thatRuss-Carol posted from Harbor Freight, I like the stainless steel pump housing.
I modified mine by mounting it to a board. Then I drilled a hole in the handle and added a switch to it then wired in a plug end to it, a 110 plug end, make sure the large blade is positive. Then I went to my battery and added a female plug to the terminals, making sure the large blade was positive. Then just let it hang outside the battery box.
When I want to transfer water, I get an electrical cord (I usemy extra30 amp cord 30ft long fromWalmart with adapters that turn it into a regular electrical cord I use this becausethe pumpdraws alot of juice and I want to make sure the cord is a good size to handle it)plug both ends in one to thethe battery and the other into the pump. Make two hose ends that are both female and screw them to the pump with short 3ft pieces of hose. Put one in the trailer fill hole , the other in the 6 galjug and flip the switch and it is transfered in no time.
Brian, Tamara, Abigail
2003 Lincoln Navigator Ultimate Edition 4X4
2004 Crossroads Cruiser CT30RL