What size are the speakers in the rear of the cab?

[drumset5994]

Self explanitory...i have the standard work truck that came with the 2-speaker AM/FM Stereo. After i swap out the stereo with an aftermarket CD player, i'd like to install speakers in the cab wall like my dad has. His 02 GMC Sierra had the same package, but the guy before him installed an aftermarket CD Player, and what looks like speakerwire ziptied (very professionally and neatly) along the underside of the dashboard, up through the door arm cover, up through and to the speakers...very nice job!

 

So anyway, what is the speaker size on the speakers behind the seats? lol

 

 

Thank you guys!

[drumset5994]

Here's the RPO code for my truck...

 

UQ5= SPEAKER SYSTEM , "4, DUAL FRT DR MTD, DUAL EXTD RGE QTR MNTD"

 

Aside from what the size of the rear speakers are...what does that mean? lol

[Wingnut]

Should be a 4 x 6.