Strange wobble/vibration going 20-30mph

[BrandonK4204]

When going any speed between 20 and 30mph the whole truck does a weird wobble then clears up as soon as you get over 30. My uncle thinks it may be a driveshaft issue. it isn't an issue with the wheels or the rotors, anyone have any thoughts?

 

[00000]

Without resorting to methods used by the Piranha Bros. it
would seem that you are asking for general vibration troubleshooting advice. Firstly, how can you be absolutely sure it isn't a wheel or rotor issue did you get a tarot reading ? You also didn't mention your tires ( which are frequent culprits nowadays despite being expensive for what you get ) I see you are in MI - do you know any gearheads locally ? call up some local enthusiasts with a Dyno and bring a lot of cold canned premium light beer !