Even on the rear support where it is metal they use the rubber pad, do you intend on using these for vibration? If so then the metal block might work OK. The unblocked bed sill served the purpose of floating except when under a load, it then went down until it touched the frame (theoretically for a short period of time).
I guess I have to wonder what the solid mounts buy you?
Yes, if we go with the metal blocks, they would be welded to the frame and have the rubber pad between the block and the bed sill. The bolts would still go all the way through, just as if we were using the wood blocks.
I don't plan on any heavy loads for the bed, so the block on the crossmember that never had one isn't really necessary, I suppose.
The advantage to the metal blocks is they become part of the frame and would be painted with the frame, the thought is to get rid of those little wood blocks from the harsh environment under the truck.
