Hot Rods model a aux transmission

I was at a junk yard to day and found a truck with aux transmission in it was a 1928 or 1929 it had a peddle on it for shifting it. is it for overdrive or under drive

this is one you hook up to the stock transmission and it has a cross member to hold the back of it look like stock

 

Underdrive with straight cut gears, not worth much unless you are restoring a truck. Even then they really aren't desirable, AA trucks had really low gears.

 

so is it under drive or over drive ?

 

under

 

Local AA has one...Can be real interesting [re: busy!] shifting it and the 3spd..