Body mount shims question

[OrrieG]

I'm confused about the body mounts. My front mounts has solid ships about 1/4" thick. The rear have hard rubber shims. I assume the front needs to be solid so the fenders, etc. align correctly, while the back offers a little cushion because the bed is independent. But looking on line it appears like replacements use rubber at all 4 locations. Won't that cause problems at the front keeping the fenders in alignment? Thanks Patrick