My floor mat is 'diamond plate' rubber roll floor mat from princess auto. Diamond side down. One seam at turn of floor to firewall, one under front edge of seats. Seams are overlapped, diamond plate removed at overlap with cheese grater style bondo file, both surfaces roughed up then glued with contact cement.
Just leave the stuff in a shed to air out for a few weeks before you install it or your cab will have that new tire smell - bad!