The classic body style uses different mounting holes than the new style...they won't work. Now it you don't have cab lights and want to use the new style it will work...I have them on mine.:thumbsup:
It's probably the rear springs slapping together...you said it lessons with the boat on it. There is a kit I believe you can get from the dealer..it is rubber inserts that go between the spring ends. Supposed to be a service bulletin out..call the dealer.;)