Was getting a very slight grind shifting from 4th to 3rd. Today I have no 3rd gear. Every other gear works fine but 3rd is "blank". I can move it to it's position but it's like there is no gear there. What can I expect when I pull the tranny?

 

If you mean you put it in 3rd gear and it revs like its in neutral, the gear has separated at the welds (I've not seen it happen with OEM gears, only first gen MFactory gears that used spot welds instead of a full weld).

Check the usuals first though (cables, shifter box, shift fork engagement tabs).