right before the "Checked Bag Allowance" section of the confirmation email (the one that says "Your Flight Receipt" -- NOT the one that says "Delta Reservation Itinerary") you will find a line that looks something like this:
Fare Details: WAS DL X/NYC 1S20.00 DL SEA 474.42KAUUA0FE USD494.42END ZP IADJFK XF IAD4.5JFK4.5
the first letter of the highlighted 8-character code is the inventory (booking code) that you purchased (you said this was "V")