I don't think balancing is your problem, but to play it safe does the a shop that did your balance have another shop to bring to, in case their machine is out of sync. Seen it happened to a friend here in Bay area. Can you borrow 2 wheels, actually 1, your spare, and another, put them both on front drive it. See what happens.
A drive shaft that's out of balance is like a bearing, it starts at around 40mph , just like a out of balance wheel, and gets worse as speed increases. Worn front end parts will usually not cause steering shake unless extremely worn. Tire tread/belt shift, or imbalance are first things to rule out. You mentioned the shop wanted to remove front drive shaft. Pull fuse #104 if 4 wheel drive is engaging, but that usually causes grinding not shaking. Were you four wheeling recently, that could have damaged front drive shaft?
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