Just came back from a trip hauling my 8000 lb. trailer. Noticed, on the flat of course, no overdrive in the mountains thank you, a shudder between 6lbs boost and about 12 lbs. For sure it's the overdrive, since kicking it out, the shudder goes away immediately. Also, less boost or more it goes away. Of course this boost is at normal cruising speeds. It's a cyclical type of shudder, almost like the tires are out of balance. With the trailer or without it does this. Truck has 18000 miles on it, 350 dually with an Ez on it. We had a discussion on tdr, about how to increase line pressure by turning a bolt on the transmission one to one and a half turns. Would this engage the torque converter" harder' to stop this? It is very annoying and feels as though you're on a rough road. If you feel as though this increase would help with this problem could you go over how and where this bolt thingee is and how to do it? thanks, guys,,, Neil