Sucks that somebody had to cut that off, a cheap wiring harness connector was all they would have needed.
Let me see what I can dig up.
Car Radio Battery Constant 12v+ Wire: Orange
Car Radio Accessory Switched 12v+ Wire: Yellow
Car Radio Ground Wire: Black/White
Car Radio Illumination Wire: Gray
Car Stereo Dimmer Wire: Dark Green
Car Stereo Antenna Trigger: N/A
Car Stereo Amp Trigger Wire: Violet
Car Stereo Amplifier Location: Mounted under the rear deck.
Car Audio Front Speakers Size: N/A
Car Audio Front Speakers Location: N/A
Left Front Speaker Positive Wire (+): Tan
Left Front Speaker Negative Wire (-): Gray
Right Front Speaker Positive Wire (+): Light Green
Right Front Speaker Negative Wire (-): Dark Green
Car Audio Rear Speakers Size: N/A
Car Audio Rear Speakers Location: N/A
Left Rear Speaker Positive Wire (+): Brown
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Dark Blue
Right Rear Speaker Negative Wire (-): Light Blue
This should be the right diagram, I am pretty sure from 1994 to 2004 the wiring was the same.
Have you bought the wiring harness that you would need if the original connector was not cut?
If not I'd get that, and get an end to replace the original that was cut, you will want to this.
And the connector that goes from that connector above, to your radio.
I suggest when joining the wires that you soldier them, and slip heat shrink tubing over them, you could try to crimp on some butt connectors, but soldier and heat shrink is the way to go, have to be careful though, because I cannot imagine soldering that connector back on will be easy, so you may be forced to go with 22/18 ga vinyl butt connectors, just be sure to crimp them well!
The Install Bay RVBC Red 22 18 Gauge Vinyl Butt Connectors 100 Pack | eBay