As new as these units are to the 4Runners, you probably won't find out without pulling it out & looking at it. Actually, if you go to techinfo.com and look up the 2009 4Runner, you may be able to pull up the Radio pinouts, which if there are pre-outs, will be noted here (may be labeled like audio unit ECU terminals or something like that). However, even if they are both made by the same company, there is a HUGE difference between aftermarket and OEM, even with the OEM unit being seemingly identical.
I highly doubt the OEM does have preouts. I have only seen or heard of one or two OEM radios ever having preouts in my many years of installing car audio.
The aftermarket unit is designed for the audio enthusiast who is very likely buying it for the features, which include the ability to easily add amps (through the pre-outs).
The OEM unit is designed for the vehicle manufacturer's specs with only a certain set of features (this also helps to make it as inexpensive to them as possible for a higher profit margin). They often even use lower quality components internally. This is especially evident with speakers.
Anyway, you'll probably end up having to use a line level converter if you want to add an amp.
