Just did a Google search and this is at the top
http://gl1800riders.com/forums/showthread.php?332489-Difference-between-Level-1-Level-2-Level-3
http://gl1800riders.com/forums/showthread.php?316930-What-are-GlL1800-Level-1-2-3-amp-4
http://gl1800riders.com/forums/showthread.php?332489-Difference-between-Level-1-Level-2-Level-3
http://gl1800riders.com/forums/showthread.php?316930-What-are-GlL1800-Level-1-2-3-amp-4