YES.
I cannot provide a guide but it isn't that difficult. Removing the stock head unit is quite easy. The adapter sold by crutchfield works best with 4Runners to fill the empty "unit" spot.
Also you should get a factory to aftermarket adapter, it should come with instructions for the wire colors.
Suggest you run all new speaker wires (depending on your needs, amperage, quality).
Run a standard 4 or 6 gauge wiring kit (sold on Amazon or crutchfield), I have my 4 channel Alpine V-12 located behind the drivers seat underneath the driver side rear floormat. My sub-amp is located in the back with the dual 12s.
Sorry I can't be of more help. Refer to other guides.
My current setup:
Alpine Head Unit
Alpine V-12 100wx4 RMS
MTX 6500-D 650W RMS
Dual MTX 12 subs
New wiring ran to all speakers
Front Doors: Infinity Kappa 6.5" Components
Rear Doors: Infinity Kappa 6x9" (slight cutting required but the door panel fits perfectly, you only cut the door metal)
Result: sounds awesome + with full tint around the truck, no-one will break in to steal it.
:guitar3: