EDIT... wait... are you talking about where the sticks connect at the front of the console, or the joystick storage area at the back of the console? My reply below was based on me thinking you were talking about the storage area.
The door doesn't snap or glue into place. It just sits there and is held in place when the upper and lower case halves are put together.
And AFAIK the piece should be completely interchangeable between the 2 and 4 port systems. Can't think of any reason they'd be different.
I was referring to the piece that fits over the joystick ports.
Thanks,
tjb
Should fit fine. Only difference is, if you put the 4 port front end on a 2. you'll have your 2 regular ports and 2 spots where the other were in the middle for the 4 port.