I hear you man, I will be doing the harsh shift TSB on mine(and installing a PPE aluminum pan) as soon as I clear out some of the 10R's I have apart already.(That'll teach ferd to be in cahoots with GM!)
stop by your dealer and get them to add dye to engine and trans oil(white for engine/green for trans)and drive it for awhile after cleaning area. We like to do this to simplify diag.