I am replacing the head unit and speakers on my '90 2+2 with non-Bose equipment. The existing rear box will take a 6 3/4 in speaker nicely. However, I haven't removed the front ones yet and I have heard that I might need to get some pretty expensive replacement brackets to put in 6 1/2 speakers in the doors. Does anyone have any experience with this and has anyone had any success using the existing speaker boxes in the front?

Thanks for you help!