I believe the "J" is a model year designator, with "Y3" being the color designator? With "Y" meaning the basic color and "3" being the intensity of that color (low = lighter, higher = darker). If it is metallic in nature, the word "poly" will appear in the paint company designation.
www.tcpglobal.com and "Library" at www.hamtramck-historical.com can have chip charts, Chrysler Color and Trim Guides, and Chrysler Dealer Data Books which can have color-related information for particular model years.
