I actually bought the steel plate from S/M but wanted to use my own speakers so used a 3d printer to make a spacer. They charged me $10 for the plate. Here’s a picture with the mounting bracket I made which is adjustable up and down as well as side to side.
Looking at the picture I posted and also while tinkering with the car yesterday, I realized I'm only utilizing one speaker. I don't recall (during install) having any more wiring for another one. Am I missing something?
Here’s my custom speaker mounted. I put a strap on the front due to the extra weight of the speakers. I was lucky there’s a couple holes in the dash and one was perfectly centered so I was able to use it. Speakers sound terrific. My helper Lola was supervising from the back seat.