Remember the reardeck speakers of yesteryear?
 

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I disconnected the four rear speakers and installed these box speakers to go with my powered mini sub. The speakers are usually used in marine applications . Overall I am pleased with the enhanced sound versus the 6 - 4" speakers the car came with ( I kept the front door speakers). I might incorporate another marine based option where I would cut holes in the parcel shelf, install shallow 1" deep 6x9s and affix the grills. This would give a more traditional rear deck speaker appearance. For now, I will enjoy the new sound. Fyi, I salvaged a tan parcel shelf, used SEM vinyl paint to change the color to satin black so all the deck components would blend vs the black speakers and sub sitting on a Saville Gray parcel shelf. As yiu can see from the photo, you can only see the sub when you look back.

I was afraid that you meant these! I had a pair in my lowrider.
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I had a pair of 4 inch round speakers with 20 ounce magnets, That mounted as the 2 you have on the package shelf. Man were they heavy, I took them out when I sold the car, and my buddy put them in his 64 Impala, He went to pass a slow car on a country road, and the driver, no signal turned left across in front of him onto a side road. Well my buddy T boned him and folded the front end of the Impala back till the frame was on the ground, and the Passenger side front tire, was 6 inches off the pavement. No one was seriously injured, except my speaker! The Impact was enough to bust the right rear speaker loose, and it came up and hit his girlfriend in the back of the head. He said it knocked her silly for a while, and I told him, she was already silly. He said yeah but now she's worse!!! Damn that was a great pair of speakers.

Rivguy: Those grills would sure spice up the old XJ40:). I will consider them if I change to the 6x9 flush mount speakers.

Jacobra: Funny story. Makes me glad I secured the speakers and amp with a combination of screws and Gorilla double stick mounting tape.