4WD systems in that era were typically part-time systems, meaning the driver engaged them manually for off-road use and drove in 2WD on the road. AWD systems, as we generally understand them today, were not common in light trucks until much later.
The owner is likely mistaken about it being AWD from the factory. It's possible:
* They're confused: They may simply be using the terms AWD and 4WD interchangeably.
* It's been modified: Someone may have added a custom AWD system after the fact, which would be a very significant and uncommon modification. This is unlikely, but possible.
If you're seriously considering buying the truck, carefully inspect it. The presence of a transfer case (a component necessary for 4WD) would indicate it was originally a 4WD vehicle, while the absence of such a system would mean it's a 2WD truck, regardless of what the owner says. A detailed inspection by a mechanic experienced with classic vehicles is highly recommended.
