So, after finding this issue with the passenger side mount, I called up my local old-truck parts place and told them I needed a couple mounts and new bolts. He asked me if it was a 5/8 or 11/16 bolt. So I went out to take a look. I crawled under, but the passenger side was so caked-up that I decided to look at the driver's side instead, since it was fairly clean. I tried getting a socked down into it, but something seemed to be in the way. I reach my fingers into it and pull out... a motor mount bolt that was sitting in the mount cup! Then I noticed another piece of steel wedged between the engine and cross-member on this side as well! Using a mirror I looked down into the mount and sure enough, there are two empty bolt-holes on the driver's side. Basically, there is not much holding this engine even in the truck itself!
Is this something they would do for say a farm truck that didn't really leave the property? What are the chances that the mounting holes in the bell-housing are going to be messed up and unable to take a new bolt!