Even though the sending units are different they do interchange. The only problem you'll see is that the gauge wont read accurately anymore. Its best to use the digital sender in place of the analog as it reads optimistically. In other words when the needle is on E you'll have 3 or 4 gallons left. When the analog sender is used in place of the digital it's the other way. You're on fumes when it reads 1/4 full.