The Mth TRUCKS are attached from insde the car. So you have to remove the upper body from the sub-floor or under body to get at the screws.
As for springs, I do something similar to the dental floss only I use a woven thread (actually old fishing line). For disassembly I lay it crossways on the springs and push into the coils with a small tweezer. I then remove the springs - one side all is necessary. You do have to take the top bolster piece off too. For re-assembly I lay the thread across the spring between 2 coils, perpendicular to the spring. Then I hold the thread with the spring between my fingers and put one end of the spring in place, and use my finger nail to push the other end down and it place. Then I pull the thread out. Works pretty well most times. I do this with all sprung trucks.
As for Lionel, I drill out the 4 rivets to remove the couplers from the new cars after disassembly of the trucks.
