Transfer case only has 3 positions, no 4x4...Help!

[benbloom]

Hi guys, Ive got a 69 k10 with a 4 speed and granny low gears. The transfer case shifter is on the drivers side of the hump, and i can't for the life of me figure out how to get into 4 wheel drive.. only 3 positions on the transfer case:
shifter all the way forward- 2 High
shifter in the middle - Neutral
Shifter touching bench - 2 low

Everywhere says that there should be 4 positions, 2hi, 4hi, N, and 4lo. anyone know the reason for this? is the only way to engage 4x4 to lock the hubs? any input would be greatly appreciated. will post pictures when i can.