Hi joeat50,
Your truck is a 52,as far as I'm aware the rearmost mounts don't have the wood blocks,just a rubber pad.
The front and mid crossmembers use the wooden blocks.
My 50 was original and unmolested and had no wood at the rear.
I remember seeing a post a while back regarding bed mounting,try a search and you may find it.
I would have done it myself and posted the link,but I have to get ready for work!