Welcome to FTE! You ask a good question. According to my owners manual, my power steering system requires "Mercon" and my transmission requires "Mercon V". So in my case I wouldn't be very happy to see a service description that says 6 Qts of P/S FLUID (i.e., Mercon) was put in my tranny since I specifically need the Mercon V. You didn't say what kind of truck or tranny you have.

Mercon is different from Mercon V. However, there is an additive which can make Mercon the same as Mercon V. Maybe your dealer used Mercon and then put in the additive? If the dealer used Mercon alone, without the additive, then you don't have the proper fluid right now.

You are doing the right thing by following up on this. If your tranny calls for Mercon V, makes sure that is what gets put in there.

Hope this helps.