Thanks very much for your time and response. It is very helpful. My 1983 originally had no stereo or speakers as I could not afford them and figured adding my own choice might be a better result. So I had the stereo/cassette deck and speakers installed at an auto stereo place some months after purchase of the car. The install included some 6x9 inch speakers on the rear deck.

I never really got a good look at what, if anything, was under the stock grills. I never thought about it because the stock grills remained in place after the speaker install. To be honest, I still am not yet sure 100% what is under that grill. The grills are most certainly held on with what is left of the 4 plastic pins and clips. At this point, my experience is that the pins will snap when I try to remove the grills. But I am reasonably sure that there is no metal behind the grills or speakers as you show in the photo of the damaged speaker.

My grills look very much like the ones you show. I did note that the single intact grill that was still attached to one of my salvage yard door panels looks quite different. It is far thinner and more flush mounted to the door panel. It also has a different slot design in the grill openings. But it also has plastic pins and clips - 2 of which snapped during removal. Other than the grill's profile/slot design and the rubber window scraper strip at the top, the new and old panels seem the same to me. But I am sure there is no metal plate there either.

Since my car has the holes in the door metal on 4" centers, I am thinking I should mount the speaker against the indoor vinyl but try to get the mounting screws into those holes in the metal. It just seems this would be more secure and solid and avoid vibration and stress on the door panel itself. Of course, removal of the door panel would then require removal of the speakers first - but I could live with that, I guess. I am pretty sure that I have seen speakers with mounting holes 4" on center. But I worry that unless I am very careful the speakers will either penetrate too far into the door void and conflict with the glass or that they will stand too proud of the door vinyl and interfere with my manual window crank.

I have even located "modernized" HT-204 speakers here (www.swedishcarparts.com/models/22-volvo-240-260-1975-1982-and-1980-1993/parts/door-panels-and-trim). They seem quite expensive but appear to come with mounting plate and a snap on grill. However, the dimensions for the mounting holes they show in the very last photo is not 4" on center as I have in the door metal. So I remain a bit confused about them.

Cheers