I recently did what you are considering. I got the sending units from Sam's Marine. You buy the senders, and also the electric upgrade. They also supply gauges that match the original gauges on your boat. You MAY not have to replace the sending units if they are working OK. Mine were an older style, but if you have the newer style you just buy the electric upgrades, at a huge cost savings. Look at your current dial. If it has two screws, one on each side of the dial you have the newer version. Just simply a matter of removing the screws, lifting off the dial, and installing a new dial with the electric wires on it. Call me at 513-378-6628 if you want more info. Good Luck!