Once the car got warm (about ten miles) I lost all the gears. The shifter is got lost in neutral and wouldn’t engage. This happed today a stop sign with out warning. Once It sat for a few mins they came back.
Looking for a little advice before I dive blindly into guts.

Thanks.

Did you check to make sure it has gear oil in it?

Set screw backed out at console?

Wrong gear oil?

clutch out of adjustment gear stack moving

turn car off put in gear and start car

Wow what a strange thread,running time/heat or whatever has nothing to do with the fact that 2 points in the shift setup have come loose,you have 2 locking screws in your shift linkage ,one at the bulkhead and the other @ the console on the g/box.
One has come loose in the system.
I have only one @ the console only the rest is uni-joints,good luck.

Until you uninstall the complete shift system, replace worn parts, reassemble, and align it, you really won't know what you have. It's an old mystery system. I've lost shifting due to bolts, a bent rod, broken bushings, worn bushings, new bushings, and I even popped off a renn linkage shaft racing, and had to reinstall the whole system between runs.

Its pretty easy, you'll find it.

Heat "could" conceivably loosen things but I agree that the screws should be checked first.

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Your clutch is not disengaging if I am understanding you correctly (wont go into a gear?). As Mark said, adjustment. The cable can stretch when warm and your clutch cable is likely too loose to begin with. In my sig below is a link to some notes and there are pics and explanations on adjusting your clutch. The clutch cable is the first suspect.

Is your ground strap in good repair? The reason I ask is that if the strap is corroded or missing then the clutch cable becomes your ground and corrodes, stretches, breaks.

Next on the list is engine mounts. When you drive for a while, they may shift. You can also have a bunch of these issues in some amount. Noting internal to the tranz is going to cause this if it was running without issue initially, and shifting returns when things cool down.