72455

Greetings to all ye Oldsmobilers! 😀
One of my future projects for my 72 Supreme is to get a stereo system. One of the previous owners installed 5 1/4 round speakers in the rear and they have to go. What is the size of the original speakers? I tried 6 x 9 but the bolt holes don't line up with the existing mounting holes and I don't want to drill new holes.

Thanks,
Dave

VC455

On my Challenger, I used masonite to make adapters. Put both bolt patterns in the adapter. It only adds about 1/4 inch to the overall height; you can use a modern speaker without drilling holes in your car.

Fun71

Back in the 80s I installed 6x9 speakers in the rear deck of my Supreme, so they will fit.

oldcutlass

I know you said you didn't want to drill holes, I would go with the adapter as described above. Mount it underneath using your original holes but use some counter sunk screws as studs to mount the 6x9's. The original speakers were an odd impedance not really compatible with newer stereos and more expensive. 6x9 2 ways are still reasonably priced and put out nice sound.

Vintage Chief

Interesting the holes don't line up on your 72'. My 71' Supreme convertible has holes which accommodate 6"x9". I just removed the single (OEM) rear mounted speaker, yesterday....it was in shreds (literally). As oldcutlass suggested the impedance isn't correct for most new/modern stereos. The OEM 6"x9" speaker has a 10 Ohm impedance...seldom if ever used on any automotive stereos these days. Additionally, that OEM speaker is an electromagnetic dynamic speaker; meaning, it has a field coil.

joe_padavano

^^^THIS. The factory didn't install SPEAKERS, only one rear deck speaker. The other hole is for the optional rear window defogger and is not sized to accept a speaker. The factory stereo used the single dash speaker for one channel and the single rear deck speaker for the other.