not sure what to do, single dash speaker

Hello, I just bought an 85 Ford F350 with a Diesel. The original push button radio was still in the dash, and although the two 6 1/2 in speakers were still in the doors they were blown. The single 6x9 in the center of the dash is gone. I have a Pioneer DEH-2000MP cd head unit lying around so I installed that. I got a kick SS deal on a set of kicker speakers (6 1-2in) for the doors. Now I am not sure what to do with the center speaker in the dash pad. I would like to get a 6x9 and install it, just to have that little kick.... but I am not sure how to even wire it in. I wired the door speakers to the rear channel, left and right, but how do I wire in 1 single 6x9 in the center of the dash. Do I wire it to the front left channel, or the front right? Or do I wire up both left and right somehow. Is it worth even adding. I am looking for "acceptable" sound quality (truck is a snow plow), but the ability to turn it up and hear it over the 6.9L diesel which is really loud! Dan1971 Chevelle SS

1989 Corvette

1996 Impala SS

Doesn't that unit have four channel outputs, you only mentioned using the rear set, you can use any of the front outputs to power the additional speaker!

Yes, I understand that but how do I connect this center speaker up to the front channel? Do I connect it to the left, the right, or both? Dan1971 Chevelle SS

1989 Corvette

1996 Impala SS

One or the other... Doesnt really matter, Butt since the speaker is more to your right than left, i would hook it to the right channel. But like I said, it really doesnt matter.UNLABELED Custom Car Club President

Figured but I just wanted to be sure Thanks for the tip Dan1971 Chevelle SS

1989 Corvette

1996 Impala SS

Back in the old 2-speaker stereo days, I used to wire up the second pair BETWEEN the active left & right (ie, the extra pair in series between L+ & R+ with no common.) BUT!!!.... It would be very trebly as it produced the difference between L&R, hence generally not bass....     And, that was TWO speakers of same impedance as the system - eg 8 Ohms (L = 8, R = 8, and between L+R = 8+8 = 16). (I believe it preserved system impedance. Anyone remember their T & Pi transforms?) Though probably not applicable here (eg, if a 2nd front speaker or resistance is required), I mention it for consideration. It certainly added to my old sound noting that my main speakers were in the front doors; the differential L+R were on the rear parcel tray. (These days bass is AFAIK rearward.)

In order to get some kind of stereo separation, I would not worry with the speaker in the center of the dash.  I am sure they placed a speaker location there for the base model vehicles that have only an AM/FM radio with only one speaker.