The 2001 GMC Sierra 1500 dashboard speakers measure 4.5 inches in diameter. The front door speakers measure four inches by six inches. The rear speakers measure five inches by seven inches.
4x6
4 by 6 in the rear and 6 1/2 up front
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.
usually 6.5 or 6.75 (same mounts, same speakers)
6.5"
Front speakers Front Door: 6-3/4" factory speaker note Far rear speakers Rear Pillar: 4x6" factory speaker note
If there are not screws in the speaker cover on the pillar then you will have to remove the entire section of interior trim. You need to use a trim removal tool to carefully pry by the fasteners.
The factory alarm on a GMC Sierra pickup truck can be reset by removing the fuse. Take the fuse out for 10 seconds and replace it. This will reset the alarm.
Pay someone else to do it!
I have found that on some websites they refer to the speaker sizes as 6.5" up front in the doors and 5.25" in the back doors with an extended cab. I have the extended cab model and bought speakers in these two sizes. When I went to install them I found that the rear speakers in the doors are actually 4x6". It is quite easy to check and from experience I recommend removing the door panels and having a look. If it is an extended cab GMC Sierra Duramax I can say with some confidence that the fronts are 6.5" and the rears are 4x6". Hope this helps, not sure if the duramax matters or not.
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.
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