Carpet problems.

i bought my 91 astro used, and when i got it, it had pretty much no interior as far as door/trim panels and carpet, it had some old house carpet crudley put down, i went to pull it up to replace it and noticed that it must be a work van because there are no mounts for the rear bench seats, but i havnt found any after market molded carpet that comes with out the holes for the bench mounts...do i have to do a custom carpet job or can i buy the pre molded carpet with no holes??? because im guess that no work vans were sold with carpet??