Won't go into gear while running

[18Fiatsandcounting]

Wow, looks like a comedy of errors, of a sort... Some thoughts:

Transmission: Where you are pointing in the first picture is the synchronizer "hub" for 5th gear. Note that the 5th synchro is a different style than the ones for 1st through 4th. Also, that "stop" you see laying there is part of the 5th gear synchro. So, it looks like the assembly might have split apart and lost part of its innards, and you'll likely find other parts in the bottom of the transmission. Would it go into 5th gear at all?

Flywheels: I definitely wouldn't use the rusty and grooved flywheels without having them resurfaced and checked for trueness, step height, etc, but it looks like you've addressed this. I seem to recall that the step for a Fiat flywheel between 1 and 2 is ideally 0.016" to 0.020", but I'm thinking you'll be fine with 0.024". I'm not sure how much the step between 2 and 3 matters as nothing rides on area 3, but maybe it's supposed to be an untouched metal surface that is used as a reference point for other measurements? Total guess on my part.

-Bryan

[Spider951]

"Would it go into 5th gear at all?"
Yes, but with "protest" - scraping and clunking sounds as soon as shifted into 5th. IIRC, 5th and reverse were the worst. 1st and 2nd weren't awful but not good either and that was with the "backward" adjusted clutch cable (see earlier parts of this thread). The final straw, however, that made me stop trying to shift into any gear (and pull the transmission and clutch....again) was an effort to shift into 5th. In May of 2021 when this trouble began, and the clutch disc fractured I had just shifted into 3rd gear and was climbing a short hill. How that relates to 5th gear I have no idea, just an observation from memory.
I think the transmission had serious problems in May, 2021, but I just didn't recognize what happened.
Thanks.