Ford Repair: Funny runner!, torque converter, steering wheel

Question
I just bought a 2001 f-150 4x4 with a 4in lift. it runs great till i get over 40mph. Once over 40mph it starts to shake real hard, and then when i press the gas it shakes more unless i goose it. Then after 50mph it doesn't really just a small shake mostly feeling when holding the steering wheel. So I am wondering if it the tranny or something else? Cause my dad said is truck would shake or buck at different time and it was his torque converter.

Answer
Unfortunately it does sound like a defective transmission. If it was my truck, I would drive it as little as possible until you find a replacement. You do have some option though. Being a four wheel drive, replacement is a little more labor intensive, but still easier. Most of your name brand parts stores have good warranties on their salvage parts programs,with amazing prices. Also, if you choose to rebuild, the price is almost cut in half if you do the labor yourself.