Side motor mounts as we know them today started in 1958 in passenger cars. I believe the first year for trucks was 1960. With that said I also believe the 1958 truck 235's had the mounting bosses cast on their block even though they weren't used.
So to answer your question, the AD trucks used front motor mounts and side bell housing mounts. If you want to install a automatic trans you will need a newer block that has side mounts and a crossmember for the trans tail mount or an old automatic trans (Hydromatic or Powerglide) that have bell housing mounts.
Maybe someone else has a different way to get around this issue that I'm not aware of.
Mike B
