There is some discussion about the wood blocks and the rubber pads. My take is that everywhere a wood block touches the frame it should have a pad (ClassicParts for one disagrees). You should also have a pad under the steel supports on the rear sill member. This link from Mar-K should iluustrate the attachements for you. And yes the front sill bolts directly to the front bed panel. it has a series of 1/4" holes along one edge for this purpose.
http://mar-k.com/bed_mounting_information.pdf