stock trans will not shift under full power no clutch shifts.
a overide shifts under full power no clutch to shift, you have to pull in the clutch if you let off the gas or you will bend shift forks. and have to stop to down shift.
a duneable will shift full power no clutch shifts, you can let off the gas without pulling in the clutch, you can down shift if you match the engine speed to the speed you are going.
thats how kevin explained it to me.