727 Transmission shifts out of order?

Hi everyone .. Im at a loss, I can't figure out why my 727 transmission that i just installed to a 383 big block. I purchase from guy that said it worked in his car fine, just leaked out of the torque converter. I got it stop leaking but it will not shift automatically, I will put the car into drive and its acts like its in 1st gear , drive 2 in second gear and drive 1 in 3rd gear??? I can't figure out what's going on? Park, neutral ,reverse is all normal and working correctly. Please help..!!