Should have taken on the Highway Before I bought it

Recently bought a 2001 Excursion 4x4 but failed to take it on the highway and get it up to speed. It shakes real bad around 65 but I can’t tell exactly where the shake comes from. Here is what I’ve fixed so far. Balanced tires, Alignment, Fixed Steering Linkage, Balanced rear drive shaft, new shocks, new brake pads (slightly warped rotors but shakes w/o braking), lubed everything, replaced all fluids except transmission which was clean, no metal in any fluids, removed front driveshaft. Checked wheel bearing as best as I can.

Sounds like something wrong in the wheels and tires department…Is it a low or high frequency vibration? Engines, flywheels, flex-plates, torque converters spin at about 2500 RPM at 65. Tires spin at about 800 RPM. I would take another look at the tires and wheels…

How many miles on the X ?

Had the tires checked? How were they balanced? Some vehicles are less tolerant to tire imperfections than others. Roadforce balancing is the only way to catch some flaws.

Well the next best bet is a bad tire or bent rim or wheel balance. (please note the above posts type faster, not trying to duplicate answers)

Going to have it balanced on the car tomorrow. Found a place that said they would check it for free, and advise me as to the problem. I took it by today and they didn’t have a lift available that could hold it so he took it on a test drive, he felt that it was driveline related, but I would need to bring it back when they could get it on their machine. Low frequency makes sense, so starting to feel it may be related to the tires.

Is the truck 100% stock, or has it had “enhancements” added to it?

I would look at the brake system, and replace the rotors that are warped, and probably recommend rebuilt calipers too, to eliminate the cause of the warped rotors in the future.