since you cut the dash I don't know if my method will work now,
I used the factory brackets and used short screws straight into the body of the unit.
I cut the Factory audio connecter and soldered the wires using color code.
Don't forget to use the plastic support on the back of the unit.
IT will take some giggling but it fits.
Color Code I was able to use:
Car Radio Battery Constant 12v+ Wire: Green/Yellow
Car Radio Accessory Switched 12v+ Wire: Yellow/Black
Car Radio Ground Wire: Red or Black
Car Radio Illumination Wire: Blue/Red
Car Stereo Dimmer Wire: N/A
Car Stereo Antenna Trigger Wire: N/A
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: 5x6.5
Car Audio Front Speakers Location: Doors
Left Front Speaker Positive Wire (+): Orange/Green
Left Front Speaker Negative Wire (-): Black/White
Right Front Speaker Positive Wire (+): White/Green
Right Front Speaker Negative Wire (-): Black/White
Car Audio Rear Speakers Size: 6x8
Car Audio Rear Speakers Location: Side Panels
Left Rear Speaker Positive Wire (+): Pink/Green
Left Rear Speaker Negative Wire (-): Pink/Blue
Right Rear Speaker Positive Wire (+): Pink/Blue
Right Rear Speaker Negative Wire (-): Green/Orange