Sportomatic - Another Problem!!

[HammerESQ]

Hello Everyone,
The next story in the saga of getting my 1977 Sportomatic back on the road. I've replaced the vacuum solenoid on the transmission, and have the car shifting into P, R, L, and D without any issue whatsoever. When I went to shift into D3, the car made a horrible grinding noise and stopped moving forward. Additionally the shifter stuck there and would not move.

With the car turned off, I was able to force it back to neutral and then into D to limp it home. The other gears seem to be working just fine.

I haven't gotten into the shifter bushings or linkage yet. Does this sound like an issue related to the linkage, or should I start looking at a rebuild?