What would have Drag Truck ran in the 1/4 ?????

I ran my ranchero at the track with the tailgate down. Counterintuitivly, i have been told there is less drag with the tailgate up (tho i do understand the theory)
It would be fun to do an a-b 1/4mile test with a consistent truck. Mph would be the telling stat.
I actually think it's just the same up or down, I know air goes in the bed and swirls down to the bed and turns back to the cab then rolls back over creating a boundary layer, with the bed down. Same happens bed up, maybe a second swirl causes an extension to the boundary layer. When I raced my Dakota there wasn't any difference except less weight.