Try to get atleast "choice" grade packer. Then it's Bludawg style, 300- 325 with fat cap down for 4 hrs ( NO PEEKING) then wrap in butcher paper if you have any, if not get some, if not foil will work too. Once it's wrapped, then you put it back on fat cap up for 2 hrs and don't worry about the IT. Use you thermo to check for probe tender. Should like you are sliding the probe into warm butter. Very little to no resistance. Once you have achieved probe tenderness. Remove and set on counter wrapped in a towel for 2 hrs. Sliced once IT IS IN. 150's -160's.
My arsenal, Stumps Clone, Two Modified offsets, open pit with grate and rotisserie,UDS, and a free to me Weber One Touch Silver 18.5" kettle