Is this partial 4wd engagement?
 

When I spin the front wheel by hand I hear a gear noise and it feels like it has more resistance than the other side. I saw a thread talking about 4wd partial engagement causes but I just wanted to see if this actually is a problem. Is that noise normal? Could it be causing the affect on my mpg that I noticed?Transfer case was in 2hi and driveshaft wasn’t spinning. I was thinking it could possibly be a push back spring or a partially sticky cable or something. It normally engages and dis engages pretty well. For reference it’s a 99 blazer LS with the 3 button system. (See attached video)

From what side do you hear this noise? Do you feel anything associated with the noise too?

There is a sliding gear on the passenger side front axle the connects the passenger side outer axle to the differential. This gear's position is determined by a vacuum diaphragm actuator located under the battery tray. You could try to manually pull and release the cable to which the diaphragm is connected. If the sound goes away it could be a matter of the cable or diaphragm getting stuck or having too much friction.

It’s on the driver side. The passenger side doesn’t feel it’s anything is spinning on the inside when it’s not engaged(as it should). And The cable feels pretty smooth at the diaphragm. I feel it moving something on the inside Of the axel on the driver side and hear the noise whenever it spin the driver hub like in the video. just not sure if it’s normal or not. I’m wondering if it’s just connected to like a part of the differential or something and I’m just hearing it and being paranoid.

Are you trying to diagnose a:

1. 4x4 issue (not engaging, or only partially engaging) or
2. An issue with a decrease in MPG, and potentially one front tire not rotating as freely as expected?

If it's 1, then Christine has offered a good starting point.
If it's 2, then the first place I'd start is looking for a brake dragging or a front hub bearing going bad. Either of those could cause drag as well as a growling kind of noise. It's also possible that it's something in the front differential that's not disengaging causing drag, but in my unprofessional opinion, that's much less likely. I'd rule out the more likely causes first, and then go deeper.

In addition to checking the easy things like what has been mentioned above , have you checked the CV joints on that side for excessive slop and play ? They can make clicking / grinding noise similar to what your video shows also when they go bad. And cause a little extra drag