My transmission did give up the ghost, but it wasn't during a shifting event. With the benefit of hindsight let me give you my best guess as to what happened.
First: The car drove fine. I usually drove in 4th because it was the quietest. I didn't have the cover on, so volume was an issue. Shifting between gears wasn't easy, but I didn't check the condition of the transmission during the rebuild of my car, so I wasn't surprised if the synchros were fried. This was a race car at one point. (Badges all over the dash!)
Second: During a photo shoot with some of my lady friends, the shifter linkage was bent. It happened to be in third gear. I could take it out of 3rd, but other gears were difficult if not impossible. So I left it in 3rd and just pushed backwards for reverse.
Third: I finally had time to work on it. I pulled the cover and found the bent linkage. I fixed it but, I couldn't get it out of third now. Apparently it had gotten stuck at some point during the few months of 3rd gear driving. I pulled the transmission out and saw the damage. The 3rd gear had kind of exploded and wrapped around the sliding gear that slides over the gears. It was working fine in 3rd still, but the only solution was to pull it out and replace gears.
Fourth: Since the car worked well in 4th, I decided to go direct drive and leave the transmission out. I need to remake my altered driveshaft, as it's a bit wobbly and the speedo gear slid off of it, but it works well for me right now in getting around town. Funnily enough it's more reliable than my small Toyota truck right now, so I need it to get to work. Once my truck is running smoothly, I'll take the Spit off the road for another month or so to fix the direct drive for good. Then its a matter of buttoning it all back up and enjoying the ride. Oh and saving up for Lithiums...