knock, knock! whats there

[mat1]

can anyone help me? when i go over bumps there is a knocking noise that comes from the front off side suspension. it only does it once or twice at the most. it seems to occur with the initial suspension action.
the whole sus seems fine generally feeling solid with good rebound. it is set on normal and has had no risers put in.
i tried a load of deer avoidance manouvers and the truck handles well with no apparent 'spungy wobble'.
one thing i thought was that it appears my tracking is a little out and i saw mention of an idler arm (no idea what that is). could this be the cause?
warranties are there for fixing stuff like this and i know mine covers suspension. however, i dont want to take it to a garage that is not used to the vehicles with out a rough idea (it seems likely that most garges wont be).
ideas would be appreciated

[marky]

Steering idler arms dont generally make a knocking noise enclosed are some pics check everything is bolted up

[Sparky]

check the off side front drive shaft were it enters the diff. mine is loos and knocks on bumpy streches of road. Can't help with a fix though.

[mat1]

i think i have found the source of the noise. after a good root around, i found that on either side of the axle there are some downward facing rubber domed stoppers that stop the suspenson going too far. both are loose and there is no logical reason for this. when i find the correct socket i will tighten them and see what happens.