On the 1960's 1960--66 had wood beds.I know they used rubber square bushings to put between the bed and the frame.It makes it so much nicer.it takes 2 people to put the bed o.You can use glue to make sure they stay in place but its helps me so much having cushion.Look in
www.truckandcarshop.com web side look for Rubber cushions for under bed.It will really help your problem
There call bed wood mounting pads page 91 10.00 kit Me i buy a few kits cus it nice having them around