Stereo install question

Had an old deck lying around and I'm tired of using the retro radio that's in there. I really didn't want to run all new speaker wire just for the stock speakers. I also wasn't wanting to spend a small fortune on the wiring harness. I'm cheap lol.

I pulled everything apart on my 87 d50 (suppose I should mention that) and am dealing with 2 plugs. On one plug, I have

White/Red
White/Blue

On the other plug I have

Blue/White (Accessory)
Green/White (Grounds out)
Red/Black (Constant Power)
Black/White (Grounds out)
Black/Red
Black/Blue
Black (Big Black wire was clipped to the original stereo mounting brackets)

So my questions would be which wires are the speaker wires? And what are the extra left over wires? Would the two that ground out be the speaker grounds? I'll still have two wires left over if that's the case.

I guess this is why people spend the $8 on a wiring harness.. Was just hoping somebody here actually knew exactly what each wire did. Thanks for any help in advance.

1987-89 Dodge Ram 50 Stereo Wiring

Constant 12V+ Red
Switched 12V+ Red/White
Ground Black
Illumination n/a
Dimmer Orange/White
Antenna Right Front
Front Speakers 4" Doors
Left Front (+) Green
Left Front (-) Green/Yellow
Right Front (+) Purple
Right Front (-) Purple/Yellow
Rear Speakers 6 1/2" Side Panels
Left Rear (+) Brown
Left Rear (-) Brown/Yellow
Right Rear (+) Blue/Red
Right Rear (-) Blue/White

Hope this helps you.

Speaker wires are as follows
White with blue stripe is
The - for left hand speaker
Black with blue stripe is
The + for left hand speaker

Black with red stripe is
The + for right side speaker
White with red stripe is the -
For right side speaker

The green and white connect to the clock
Plug and the cigarette lighter
Blue and white connect to cigarette lighter
As well as the ACC position
Red and black connect to dome light
As well as fusible link

I'm a little late on responding. I actually decided to pop the speaker covers and just take a look. Was scared the covers were plastic but was pretty relieved when they turned out to be metal. Ford could take a lesson there.

Thanks for the input. Joe, you were exactly right on the speaker wires. And thanks for clearing up what the extra wires are for. Appreciate it.