5 1/4'' front and rear
Doors 6 3/4 Rear pillars 4x6
The stock size of the speakers in a GMC Sierra are 4x6 in the rear. If they have not yet been switched out with an aftermarket, they will be the 4x6.
The 2001 GMC Sierra has 6 1/2 inch speakers in the front as well as in the rear.
The rear speakers are 6"x9"
There are two pairs of speakers, a pair in the doors and a pair in the rear pillars. The door speakers are 6 1/2". I'm not sure of the rear speaker dimensions, but if you call Crutchfield or look at their site online, you can input your truck details and they will tell you what size the rear ones are.
The speakers located in dash and in the rear of an extended cab model will be 4x6 speakers. These speakers are used up until the 94 model.
I believe they are 8" by 9"
6.5 in the front. 6X9 in the rear.
The front door speakers on a 2000 Pontiac Grand Am Se are 4x6. The rear deck speakers are 6x9.
The 2000 Chevrolet 1500 Z 71 front speakers measure three by five inches. The rear speakers measure four by six inches.
6 inches in the front. 6 x 3.5 in the back.