Front end Chassis Issue, 97 Ford Super Duty

I've had several vehicles that required spin balancing and tire trueing on the vehicle to cure vibration. Sometimes the vibration may feel close, but may in fact originate from the rear.

Driveline out of phase or misaligned possibly.

TCC ruled out by testing in neutral and coasting.

You may need a truck shop that can run it on a chassis dyno or on a lift at speed to find the cause.