Only one truss rod?  My series 1 has dual truss rods, I thought they all did.

Single truss rods until mid-'77. 


That particular bass has a replaced truss rod, but it was a single to begin with.

I do remember looking at the control cavity on CL and thinking something was a little odd, but i don't know what.

Although I think Hieronymous' '75 double neck has dual trussrods in one of the necks, but probably an exception.