2001 Silverado 1500 not getting power to front wheels

bashington · January 12, 2019

I've had a problem with the 4wd on my truck since I bought it. The problem is that everything indicates that the 4wd is working but I get no power to the front wheels and the rear wheels just spin, whether in 4hi or 4lo. There are no codes on the dash and I've checked with a borrowed scan tool. When I press any of the 4wd buttons it blinks for a second, clunks at the transfer case, then the light turns solid and I'm in "4wd". While in 4lo the gearing is reduced like it should be, just acts like 2lo. The transfer case is a GM 246.

Here are the parts I've replaced.
-New dash switch
-New front axle actuator (I've had it out of the differential and plugged in to verify the plunger goes in and out.)
-New ACDelco encoder motor on the side of transfer case
-Cleaned up the ground on driver side frame rail

Here are the things I've tried:
-One front wheel in the air and the other three on the ground while in 4wd, the wheel in the air turns freely (from what I understand it shouldn't though, as it is supposed to be connected to the other front wheel)
-Both front wheels in the air and the back two on the ground, when you turn one front wheel by hand the other wheel spins in the opposite direction (indicating that they are indeed locked together?). Also, while in 2hi I can spin the front driveshaft by hand, and while in 4hi/lo it can not be moved.
-All four wheels in the air:
2hi - rear wheel spins and front wheels do not
4hi/lo - one rear wheel spins (open diff) and the front wheel on the opposite side spins (also open diff)

So I am thoroughly confused and my next guess is either the front differential is toast (no weird noises or grinding)
OR
what I'm leaning towards is the transfer case clutches are worn out and it has enough friction material to spin the tires while in the air but on the ground it doesn't.