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.