well i'll answer my own question - turns out i didn't need the mounting bracket. years ago i had mounted some simply awful Tandy 3.5 speakers in the housing that holds the original 4x10 speaker. afer reseaching newer speakers and not wanting to spend a fortune on something i might not be able to hear anyway, i bought these- Boss SE322 CHAOS 3.5-Inch 140 Watt 2-Way Speaker on Amazon for the tidy sum of $11. the good news is they fit! it's tight around the heater cables but with a little finagling they work. even better news is they sound really good at least to my ear. i matched them up with the Boss 6x9 for the rear after chasing out the mouse (how???) and got a Pioneer head unit and WOW - i'm BUMPIN'! now to figure out how to mount the unit in my stock dash without wrecking/drilling!