1990 bronco 2 standard shift lever question

[90bronco2]

Ok so I just got another bronco 2, which needed a transmission. The transmission is installed now. The new transmission came with a new, what I'm calling the shift lever mount haha. This is the plate with the 3 T25 TORX bolts. So I'm trying to get the old one off my shift lever, reason being the new one has a nicer upper seal, and a gasket my old one doesn't. The shift lever has what seems to be an all thread, and a nut on the longer side. Is this an adjust for the shifter? How do I get this plate off? I've tried puting another nut on to lock the first one to try and screw out the thread but it won't budge. Thanks
ED