Just in case anyone else has the problem I’ve experienced, here is what happened. So in a rapid shift from 2nd to 3rd gear (a la drag race), the gear never landed in 3rd, and the shifter went completely loose. It would travel completely forward and back with no resistance, and it was stuck in 4th gear. I knew it wasn’t major (like a broken shift fork or even gears) as it drove just find, no grinding noises, and nothing seemed to be broken internally that would cause a major rebuild. I think I got lucky though!
$100 in parts for 2 interlock arms and pins. I went ahead and replaced the synchros for 2nd and 3rd gear, 2nd driven gear, and also the 1-2 and 3-4 shift fork, as the plastic tabs were just about gone. Seals were also replaced as well. Wow, what a difference it makes! Shifting in lower gears is SO much easier and is buttery smooth. No more problems shifting into 3rd at high speed, works like a charm.