Hello,
I apologize for assuming everyone knows what "PM" means - I didn't when I first started browsing web boards like this one. PM is the short form for "private message". It's a feature you can use on this web site to contact a member directly for a discussion on the side, without having to "waste" space in a regular thread. Especially useful when working out details on a sale, passing along personal information like phone numbers, etc.
As for the speaker brackets... I have several styles that work with all A, B, and E-body cars ranging from '63-'76 (and some trucks/vans/Ramchargers). They enable you to replace your old single dash speaker with a pair of modern 3.5" or 4" two-way speakers for updated sound systems. The closest thing you'll find to achieve stereo sound in these old cars, short of hacking up your kick panels or doors.
Quite a few members here have used them and can attest to their quality and usefulness. Let me know if you have any other questions.
Jerry