shaking all over the place?

[PGSigns]

One more thing with the rear pictures is it looks like the center pin has been spinning with the spider gears. That should not happen. I know you don't want to hear this but with all the issues you have had with this truck I would start from the back and work your way to the front and check everything. They rear needs to come apart and since you have it open may as well start there. The brake lines are not attached as they should be and it looks like an old one still hanging in a bracket in the one picture. I would inspect them from front to rear and look at the rubber hoses to make sure they are 100%. While you are sorting the rear end pull the drive shaft and service the u-joints. Pull all the wheels and inspect the brakes, check the tires for bad cords. Check the bushings in the trailing arms. Pics were requested of the front end and I think you had them in another thread. You are at a disadvantage being on that side of the pond for parts and will make this adventure much more difficult. I assume you got this truck sight unseen and did not take it for a good shake down before you got it.
Jimmy