When Toyota introduced its T100 three years ago, it was the first full-size Japanese pickup in a market as American as apple pie. Although Toyota initially refrained from using the full-size label, it could carry a 4x8 plywood sheet between its rear wheel wells and three adults between its doors. But unlike other large pickups, the T100 arrived with a small V6 in a market where big, brawny V8s are king. It also came regular-cab-only at a time when demand for roomier extended cabs was increasing. Sales languished. But while some pundits called that first T100 an outsized flop, others suspected it was merely a foot in the door. Toyota's T100 Xtracab has proven the optimists right. A 21.7-in. stretch provides the rear seat and lockable storage space T100s have lacked. Though they still lack a V8 engine option, a potent new V6 is another reason more big-truck buyers are putting the T100 on their shopping lists.