Radio install ?'s

[rb70]

My 70 Cuda has a big opening where the radio goes.

Is there a bracket or something, that hold the radio in the slot?

What size are the 2 speakers in the dash?

Are the rear speakers 6x9 or 6x7?

[Moparal]

2 screws holds the front in on the bottom, then a flat bracket brace on the rt side rear....6x9