I think Heavy is right! I have had a 76 4001 and I own a 84 4003!
I think they always have had the double rod set up thats what made the Ric so unique!
I also believe that Ric just made refinements to the double rod system in 84 accounting for the more baseball bat feeling neck and wider string spacing like on my 84!
I remember my 76 had the dual rod system because it was the only bass that I wouldn't set up on my own back then..
I could be wrong I'm just going by my own findings
I think they always have had the double rod set up thats what made the Ric so unique!
I also believe that Ric just made refinements to the double rod system in 84 accounting for the more baseball bat feeling neck and wider string spacing like on my 84!
I remember my 76 had the dual rod system because it was the only bass that I wouldn't set up on my own back then..
I could be wrong I'm just going by my own findings