IS there some kind of trick to removing the king-pin assembly from the trailing arms? They have crappy 2-flat sided bolts which are impossible to get out. Is there some special tool or knack to getting them out?

Remove the nuts from the bolts and then turn the head of the bolt either way untill you feel it loosen up.

this should the allow you to remove the bolt completely, as it sits in a groove on the link pin, therefore not allowing the pin to push out until the bolt is out of the way.

Once the bolt have been removed the pins should push out with the help of a pin punch.

theres a little tension on the trailing arms so be careful.