There is a very good chance it has nothing to do with your linkage. If you expose the steering column, there should be a plastic ring that holds a cord attached to the indicator needle. On my '87, that ring had cracked and the cord was thereby loosened causing the needle to be off. I used a zip tie to attach the right side of the ring (where the ends join) to the shifter shaft, and gradually tightened it until the proper tension was returned to the cord. I had to readjust it a couple times because of stretch in the tie, but it has read absolutely true for months.