tranny fluid mix ok??

[palmerc]

My dad just got his '00 7.3 back from the shop on a full maintenance deal....
He is low on his tranny and oil but the shop seems a little confused on what transmission fluid they are using. I have Mercon V at the house, can he add that to whatever is in the truck? Their response to me about whether they put in Mercon or Merc V was "we put in a blend that certifies up to Merc V so just top it off with Merc V" Does this sound ok to do??