"I want to get a fuel gauge instead of using a stick, although the stick is accurate."

Stock Dodge ohm value for gas gauge is 10 ohms (full) to 73 ohms (empty).

Fuse rating = (watts/volts) x 1.25

Say the calculated fuse rating is 2.2679 amps, use a 3 amp fuse. Say the calculated fuse rating is 4.9431 amps, use a 5 amp fuse.