I think at this point if it's confirmed that it's the gears buy some triple a for $ 50 and drive it till it breaks , the gears are so deep in the trans that when they go everything else is protected , the thing is they can go in a day or in three months , who knows ....get triple a and cover yourself ....they also will let you sign up when your already broken down so you could just wait for it to go then sign up ....just an fyi ...
I would advise against this if you're trying to rebuild yours as I'm sure $ 500 is an estimate for parts , as you never know until you get in there how bad it is...if your rebuilding yours check into upgraded clutch packs and valve bodies , the torque convertor not so much but clutch packs for sure ...might as well beef it up a bit while your there .
My trans experience comes from the torque flite series of trans. Not be so much the toys so you may want to ask around about such things . But upgraded clutch packs are always good imo.