Luke - From what I've found today and in the past, there is a picture in the 1947-54 Chevy Truck FAM, but it doesn't give any measurements or specifications on where to mount those pieces.
The couple of vendors I see advertising them, Jim Carter and Chev's of the 40's, say their kits come with instructions, but they don't offer them separate from the kits.
I think your only hope is to find someone that has them installed originally (for measurements), or has a copy of the installation instructions they would be willing to share.
Sorry I can't be of more help.
