Can't get the diff loc to break free so gonna have to open her up

Stuck diff loc:

 

That's not the diff lock...

 

ah yup he's right that not the diff lock

 

That's the High/ Low linkage. Does the Discovery I have an interlock on the TCASE like the DII does? If so, that explains why you can't shift from H-L.

The diff lock is just above the front output flange, with the small linkage attached.

 

Yes, D1 has an interlock, it's easy to delete.

 

It's all diff lock to me..... still still stuck, still gotta tear into it....

 

I'm pretty sure the interlock is that plug/cylinder seen in the bottom right of your video.
I also think the truck has to be in Neutral to shift Hi/Lo. I say "think" because I can't recall 100% and I'm not by my truck right now.

 

What I cant figure out is that when the diff loc lever is to the right I can shift between high and low no issue. When its to the left it will not shift between high and low. The diff loc is not stuck and can be shifted by hand (tranny and t-case is still currently out) I was unaware of the interlock but since I can shift between high/low I know thats not seized. any thoughts?