That 47-50 spare tire mount is like hens teeth, especially the part you're missing. And if they can be found they're EXPENSIVE $$$. An option would be to go with a 51 and later style, which is a single bar run diagonally and hung from long bolts. They're more readily available and should bolt right in to your truck. I found one at a wrecking yard for my '51. An illustration is on Section 10, Sheet 2.00 of the Factory Assembly manual. For the very few times you might need a spare tire, they're not that unreasonable to use.
