two 4 1/2s and two 4*10s.
back speakers not sure what size
they are 4 by 8
this might help you: http://www.justanswer.com/questions/194b5-1987-gmc-suburban-4x4
33gallons on a 1987 20 series silverado suburban
4x6 are the size of the door speakers on 2004 GMC Sierra. Standard cab
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.
All four speakers are 4x6. I just ordered new 4x6's for my 93 GMC Sierra, and that is the stock size.
What is the size of speakers on the dash of a 1991 gmc single cab
6.5" round door speakers
about 40 gallons
The speakers in a 2006 GMC Sierra 1500 crew cab are 6.5 inches. However, the speaker manufacturer will refer to this size as 6.75 or 6 3/4 inch speakers.
The 2001 GMC Sierra has 6 1/2 inch speakers in the front as well as in the rear.