I'm assuming from your signature that it's an MT2. To check your balance, you have to remove the dogbone, so there is nothing touching the axle. If it has cvd's, then I don't know what to tell you. I don't advocate disassembling cvd's unless you are fixing or rebuilding that part. Less chance of losing a setscrew and pin next time out.
Maybe set up a hub carrier in a vice, with an axle on bearings...

I don't know what the weight difference is between garden dirt and dog poo, but either one will throw balance off. If you ever see the fast guys at the track, they get out the brushes between runs and scrub all the dirt off the tires to keep their wheels spinning true. I don't go to that extreme(I'm not one of the fast guys at the track either...coincidence?), but I do give most of my wheels a balance attempt. Not only does it help handling and speed, it reduces the load on the bearings and hinge pins, and reduces stress and vibrations that can cause screws to back out, causing your truck to jettison pieces necessary to continued operation.