Help Please
 

Im am hearing a loud squeak coming from the rear of the truck. I am pretty sure that its the leaf springs. I load a bunch of survey equipment almost a full load i really dont know the exact weight but the truck is a 2001 4x4 and its had its fair share of the bed being slapped full of stuff rideing around construction jobs and in the deep neck of the woods and with a lot of weight in the back and hitting holes at 10-15 mph and towing a boat thats 5500 lbs i think thats my problem now whats the solution to stop the noise and im planning on just replacing them anyways so where can i buy some oem or even better leaf spings.