https://www.musclecardiy.com/transmissions/how-to-rebuild-chrysler-a883-4-speed-transmissions/#:~:text=The%20A833%20is%20a%20side-loaded%20transmission%20with%20all,The%20outboard%20design%20requires%20an%20additional%20mid%20plate.

Quick overhaul hints with pictures, as mentioned the two syncro hubs have different lengths. If you scroll down the pictures it shows the hub differences.
And how is the endplay of the unit? How much movement if any of the input and output shafts in and out? That can cause your trouble as well.