Ive been tinkering with different set-ups to smoke on a flat top 26 and have found good success with the following method.
The set-up
Home made wire basket filled with lump/Kcomp placed on the bottom of the grill. About 8 lit briqs to get things going along with a few chunks of oak and pecan wood.
Original grate at the normal height. Four 3" elevator bolts for the raised grate.
Diffuser consisting of aluminum pans wrapped with foil
Cooking grate in-place
Spares on. I usually start with two bowl vents open to get to temp than close one for the cook.
Just a couple pics I liked