I finally got the speaker grill off the right rear speaker (BTW: my '95 124 is a little different than the description given in the DIY article. There's a circle clip that needs to be removed from a plastic post from the trunk side) and confirmed that the speaker is bad. It's a 3-way with raised tweeters, but the paper woofer cone is bad.
The speaker is mounted in a plastic ring that clips into the sheet metal. Does this ring separate from the speaker easily? Otherwise, what's a good way to mount a replacement without cutting sheet metal? The contour of the metal deck isn't flat, so I don't know how I'd get a good seal, fit etc.
Thanks to anyone who's "been there done that"
Tom