The photos of the shims are your caster shims and yes, they are an important part of the front end alignment. Those do not appear to me to be stock and they seem to say "4 degrees" which may be a bit too much. I have a manual for a '51 1/2 ton and the caster should be 1 3/4 (plus or minus 1/2) degrees. The thick part of the shim should be toward the back, thin toward the front.
Kent
