Alright Im looking at the part numbers and the 3390 is for 1985-93 ram50s and then i found part number 4389 which is more expensive but says it fits 1979-84 ram 50s.... are there any differences at all between the two? I guess what im asking is which one should i go with... and the only place where i can find the 4389 one is on grants actual site and its more money..