I would like to add a subwoofer to my stock system and wondered if anyone has done this?

Not Yet, But possibly soon...

I normally use an aftermarket head unit and use RCA output but I like the factory system other than the need for more bass. Would I connect into the existing rear speaker wires and run into the speaker level inputs on my amp?

This is one solution. However, I would get a high level to low level converter instead of running them right into your amplifier. (But I suggest you get a new headunit).

Would this cause a loss of signal to the rear speakers or the sub amp to have them tied together?

I believe you would have problems trying to power and AMP and Rear speakers off the same channel. I think you would need to run all 4 off the front channel. (Or get a new headunit).

My other alternative would be to install my Alpine head unit and redo the entire system. Does someone make an install kit for a DIN into the 2001 dash? I noticed that it is different in shape than the previous models. Anyone done this?

Yes! I installed an Alpine into my truck, and it DID make a hell of a difference. I put a CDA-7875 into my truck. It has 60watts RMS, and 3 outputs + 1 sub out. Heres a link to it. Its an awesome unit. If your serious about installing a custom system, check these sites here. This one is for a JL Audio Stealth Box, and the other is to a MTX Thunder form. I have heard great things about both. Of course, both of these is assuming you have the Club Cab. If you have the standard, or quad, you will have to ask around for ideas, there are plenty.

I also got my kit and plug for the stereo at Best Buy (In Missouri) So they DO make one you can use... Good luck to ya! Let me know if you need more info.


-Dave

Your best bet, if you do not want to replace your factory head unit, is to run all of the Dakota's speakers off your front channel. I am not sure how much, but it will effect the ammount of power to each speaker (off the front channel). You would probably drop the ohm load as well. If you don't want to replace the head, then you will need to get a High to Low Level Converter -> This converts your speaker wires to RCA Jacks. They will be better then running it into an amp that has high level inputs.

Then you hook that up to your rear speaker channel, and run a set of RCA'a to your thunderform or Stealth Box.

IMO the stealth box would be better. JL makes the best damn speaker i have ever heard in my life. Now saying that i want to let you all know that I Have Not had the oppotunity to hear the Stealth Box OR the ThunderForm. I also have never heard MTX before. They are both so expensive, it is likely hard to talk to someone who has tried both.

However, i have heard many kudos between the two of them. The JL Audio speaker is one 8" dual voice coil speaker. FYI, i have heard JL's 10's THen thump the hell out of many 12's i have heard, as well as 15's. As for the ThuderForms, i hear they are good, but you will want to put your own amp on it (Dont use theirs). They have a higher resistance, and will need to use a Mono amp to get the appropriate load. There is another post here talking about this subject... Click Here To View It...

But still, yet again... I suggest your replace the head.

My 2¢
- Hope it was well spent :)

-Dave