[chevyguyase]

I have a hard time with your description of the problem and I don't recognize the part in your hand. I've had a lot of these apart back in the day though. I'm assuming all the gears mesh with the cover off? Can you shift to 5th and reverse using the linkage that is in the trans now with the cover off? If you can't the problem is in that linkage set up. If every thing shifts with cover off the problem should be in the cover and linkage in the cover. I've found that the roll pins that secure the shift rods to the forks can shear off but look good. you can try to run a fine wire through them or shine a light through them. If they shear off, the linkage will be out of time and lock up the linkage. check all of the roll pins including the ones in the linkage in the case. Did you have 5th gear apart? Keep us posted if this doesn't help