They are talking about the pins that hold the fixed end of the bands inside the trans. When I got my racer, there was evidence that that had happened before, but only on one side. in your case, both sides would have to have broken, bent or ripped loose. seems unlikely to me.
not to second guess you, but did you get the shifter hold downs pushed down tight and their bolts tight. something to try would be removing the diamond shifters and manually moving the shift collars inside the transmission. with the diamonds removed, look down in the bore and you will see the groove that the shift pin rides in. stick a large flat blade screwdriver in there and move the shift collar either in or out and see if you have drive (If memory serves me, moving them in toward the center of the trans should get you forward). Do this with the engine off. you will probably need to rock the machine a bit to shift it this way. If you still don't have any drive, then it's time to yank the trans and split the case to see what broke... (my suspicion would be a broken input shaft based on what you've said so far)
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