Using wood to raise a bed????

[36chevy]

Hey guys I really happy to be here after a long break from Old chevy Pu's. I just bought a nice little 57 but I not sure I like how high the rear as compared to the front. The guy I bought it from raised the bed with wood 3 or 4 inches. Has anyone every seen this before? I am tryin to figure out if I need to remove the wood to lower it or can i just lower the extension on the rear leaf. When I was a kid we used to lower our leafs with blocks. On this truck they have the leafs mounted above the rear end. Any advice on what steps I should go about would be greatly appreciated .