My V10 was using coolant too. I took it to Fullerton Dodge. They said my radiator was leaking from where the plastic tanks attach to the core. I never saw any leaks. I bought a new radiator and installed it myself. After that I did a coolant system pressure check and it held pressure. Since then my V10 has only used a very small amount of coolant and then stopped using coolant. Probably, it was replacing a small amount of air in the system during the cool down after being hot.

1998 Dodge Ram 3500 Quad Cab 4x4 Long Bed V10 Automaic Overdrive and 3.54:1 axle ratio