You need an AC/DC power supply, 12volt 10 amp, will do for any Factory Radio unit
These look like a Laptop Power supply, usually $35-$45
You can just cut the 12v plug end off and splice the + and - wires or get a Female plug that matches the plug on the power supply
You need it to feed two 12volt lines and usually 2 grounds on a radio
1998 Ranger wiring diagram here:
https://www.therangerstation.com/tech_library/pdf_documents/1998_Ranger_Radio_Wiring.pdf
Fuse 28 red/black wire is NOT hooked up, it MUTES the radio when starting engine
Fuses 20 and 29 wires do need to be hooked up to the 12volt power supply
Yellow/black and green/purple wires
You don't need the fuses, power supplies can fail but just stop working, they never do voltage spikes
Green/purple wire is needed to Hold Presets and Clock time
Yellow/black is the key on and off 12volt power, you will just be using the on/off switch on the radio
You can also hook up the Blue/red wire to 12v, its for the back lights on the radio, pin 1 on diagram
This diagram show 3 grounds, so these connect to the "-" wire on the power supply
You also need an antenna to get Radio stations
Any 8ohms speakers can be used, and you just need 2 but can run 4, up to you, there is a Fader control so all sound goes to front 2 speakers
Make sure the Powered Sub has an 8 ohm speaker wire Pass thru, not just an RCA jack plug in
You would hook it up to the Left Front speaker wire and then continue that wire to the regular speaker
Some powered subs can be hooked up to both left and right, even better, then out to the regular speakers
These pass thrus act as 0 load so doesn't effect the impedance the radio amplifier sees, it just uses the "speaker level" signals to pull out the lower frequencies