Hello everyone,
I just wanted to post the outcome of my noise, vibration, and shifter problems for anyone who experiences (and searches on) these symptoms in the future (isn't that what forums like this are all about anyway?!) I'll post this everywhere I posted this issue originally to hopefully help someone out someday....

It seems that the "VIBRATION DAMPENER" of the propellershaft came loose. All of the internal rubber that had connected this heavy outer steel ring to the propeller shaft had disintegrated, and it became loose, sliding BACK of the driveshaft. It was probably happily sitting back on the propshaft, until I hit the brakes to avoid hitting the a**hole that pulled out in front of me. It then slid forward on the propshaft- clanking, banging, rubbing and interfering with the shifter linkage.

The shop was very honest, cut the offending dampener off, and called me to let me know that I did NOT need a transmission after all. What's more- they didn't charge me for staying open late for me to limp it to them in first and second gear from across town. I'll replace the dampener soon....

Thank you too all of those who contributed their thoughts and guidance on this topic. You make this forum a great resource for the rest of us! -John