Have you actually verified that by doing as suggested and disconnecting the linkage then moving the shift lever full back?
You will not know for sure until you do this.
While the linkage is disconnected, move the lever through the gears and make sure there is a firm detent at each gear, no slop when it's in a detent. There are rare cases where the shift shaft that is swedged into the roostercomb can come loose and cause excessive play.
Yes, this is exactly what I did and why I'm confident in saying it's not the linkage. I spent at least an hour going back and forth between the shifter, the linkage and the lever on the trans adjusting everything to ensure there is clean engagement with each gear and no binding in the mechanism. It wasn't that way to start (felt "tight" at either one end of the range or the other), but the last tweaks left it with good freedom of movement from P to 1.
If there's something going on w/ the rooster comb, I don't know at this time. It will be one of the next things I look into when I crawl back under the car.
