Hello all. I am new to the board and bought a 1973 Buick Lesabre 2 door with the 350/350. Frame and interior in great shape. Previous owner painted the car a color shifting red.... original factory color was green. I bought the car when my 2008 Ford Expedition decided to have a fight between the ecm and throttle body. I took the opportunity to go old school with NO computer, etc. so no electrical (read: computer issues) to deal with anymore. I paid $4500 for the car and have put another $8,000 into it. I knew it would take some tlc, but the laundry list of fixes is long but distinguished: rebuilt transmission (twice-shop screwed it up the first time- second rebuild on them), new water pump, new fuel pump, new power steering pump, new brake master cylinder, new exhaust, replaced left exhaust manifold, new fuel send, new shocks/springs front and rear, new tie rods/ball joints/ idler. etc. on front, new calipers/rotors/bearings on front, new rear wheel bearings, new radiator, new egr valve, new tires, new washer pump motor, a little bit of body work for rust behind front left tire and passenger door, new heater control valve, replaced rear window "chrome" (aluminum) surround and found missing piece online, replaced oem bumper jack, and a few more things I am sure that I am forgetting. I do have one question... with all of the work done, there is still a intermittent low rumble with associated vibration that can be felt in the floor board and steering column while driving. It only happens in 3rd at highway speed 50-75 mph and is most pronounced at 55 and 60-65 mph. Also, at times when decelerating with no gas pedal usage (coasting to a stop for a stop light, etc.) there is alot of noise that I am guessing is from the transmission and the car slows down like throwing out an anchor. When it runs smoothly and quiet, it is a DREAM to drive. However, I am getting frustrated with having it run smooth as silk on day (or part of a trip, etc.) and the vibrate, low rumble and no coasting at other times. I am suspecting that the transmission shop where I live screwed it up again... Suggestions?