The names of the files for the table extenders downloaded from printables may not be right (front back left right). If you print a full set you will be fine for a “standard LR3 build”. You can verify the files in a slicer and see where each one will fit. Like I said I just printed a set and they were good.
I’ve updated my first post with this info as well as here.
Here’s the thread were this came to light.