When I had the trans rebuilt, I replaced the neutral safety switch. I assumed the switch was good (was a new NAPA Gold part). Well, on a whim, I ordered a NOS NSS from EBay and that resolved the issue. So much for "gold" parts.
Yep, We have seen a few threads about replacement 3 prong/dual function switches from aftermarket. Evidently there was a slight change in the depth of the switch nose. Happy moparing