8 speaker conversion question Options

[madmods]

I bought a set of door panels from Ti that have the extra midrange speaker. I have already replaced the tweeter and the bottom speakers with a 6 3/4". My question is: Is the hole there for this 3rd speaker, or do I have to make one? If theres no hole, and I make one, can i just screw the speakers in there with some sheet metal screws. I saw this bracket in the pic below and didn't know if I needed it or not. I haven't removed my door panels yet to answer this question. Also should I wire the speaker parallel to the 6 3/4? Thanks in advance