Help Help And Help!!!!!

I was just getting everything ready to put project armour-dillo to a rolling chassis when i noticed one of the rear leave springs isnt looking right
the nut pin thing that goes through all the leaves has lost the nut and the really small leaf has come away.what do i do????
someone said just fix it to the axle as is and the pressure from the U bolts will clamp it tight anyway...???? is thier no way of hoding the round head on the top and putting a Ny-loc nut on the end??????
Any help would be muchly appreciated???

I can't see a problem with leaving the nut off, but I'd do it right and put it on anyway. Locking pliers would stop the pin spinning.