Need help a.s.a.p please.

My 727 transmission in my 1971 duster won’t shift when I’m trying to manually shift it with the shift lever under the car but when I dropped the throttle body it shifted just fine when unbolted from the transmission, then when I bolted it back it wouldn’t shift through the gears again??? I’m trying to see if this rod might be the problem, does anyone know what this rod is, I attached a pic. Also if anyone has any suggestions I would really appreciate it.