I am trying to figure out if the 4wd on my 67 F250 is actually working.

My question is this: if the front shaft is spinning does definitely mean that it is receiving power?

With hubs locked both front and rear drive shafts spin when I'm in 4H (as you'd expect) but with hubs UNLOCKED the front shaft does NOT spin when I'm 4H. I'm trying to figure out if 4WD actually works in this thing. It IS hard to turn sharply when in 4H or 4L. If hubs are locked and front shaft is spinning does it mean that 4WD is working? or could it be the ground that is turning the front shaft because the hubs are locked? Is there another way to determine if there is power going to the front shaft? (Front shaft NEVER spins without hubs locked regardless of transfer case setting. I was hoping that the front shaft would only spin in 4H when hubs are locked. Only time when front shaft stops spinning is when hubs UNLOCKED.)

 

If the hubs are locked they can spin. But chances are if it is very hard to turn then yes your 4wd is working. Good way to find out is disconnect your rear driveshaft, put it in 4wd and try driving.