Award bookings on partners will be partner coded using partner booking classes no matter whose miles you use to book and T is the LA booking class for Economy awards. I would expect it to be treated like a regular full Economy class booking. As far as I'm aware, DL is pretty much the only airline that has a Basic/Light Economy award booking class (NE) for coach which can only be booked using DL Skymiles. You can't book DL Basic Economy awards on any itins that include partner metal in them and they will always be booked as Economy/Main type awards for coach cabin.