I picked up these two floorjacks at an estate sale for 25 bucks a piece. I'm guessing they are the S4 model. They are huge and heavy. I've tinkered with one and after topping off with fluid it lifted my truck. It is leaking down under the silver plate that bolts down with the light on top. Do they make a seal for that square metal piece that screws on? I would like to get one functioning well if possible. If not for that price they will just be cool shop art, lol.