“You could buy full sized Ford 150 4x4 for less than $3K.”
Actually you could not, the F-150 did not exist until 1975 and it was initially only available in two wheel drive.
“The 1959 model year was the first time Ford built light truck 4x4s in-house. Up to that point, they were farmed out to Marmon-Herrington (M-H) for conversion using a Dana 44 closed knuckle front axle.”
http://www.therangerstation.com/resources/history_of_4x4.htm
Now they might have called them a different number, but they were selling 4x4 pickups long before 1975.