Transmission will not shift into third or fourth gear

I recently changed my alternator and doing this the right front axle has to come out. Everything went pretty smooth putting everything back together and when I test drove it the transmission fluid came out because I did not replace the axle seal. I replaced the seal and had no leaks but since. I lost some fluid the transmission was slipping just a little bit. So I topped it off with Mercon V and now I only have first and second gear and reverse is fine. What I am not sure of is, does my vehicle take Mercon or Mercon V? Most stuff I read says the V but my dipstick says Mercon. Can you mix the two? And also the vehicle runs great and sounds good, it just will not shift.