What are they for, for example if they are for a Disco are they the easy fit or the chassis mounted ones?
I've fitted easy fits on my Disco on to the outriggers, and if thats what you've got then a tip.
Once in place and alll tight, put your weight on them and make sure they dont move, mine did. So when i checked again i was able to get another couple of turns on the nut to get the tension right.
Just a thought.