Since you didn't tell use the engine V-6 or V-8 [http://autorepair.about.com/library/firing_orders/bl-Chevrolet-firing-91.htm Try looking Here] Good Luck and Remember.
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What engine? V8? 18436572 for chevy 1991 silverado v8 350 diagram
All the speakers in a 1991 Chevy Silverado should be 4x6 if they are stock.
3200
85 mph.
you might try www.haynes.com
I need a diagram for the 1991 Chevy blazer to see where the 3 hoses go to coming off the transfer case.
For a 1991 Chevrolet Blazer with 5.0L, 5.7L and 7.4L engines the firing order is 1-8-4-3-6-5-7-2 The distributor rotation is clockwise. Here's a web page with a wiring diagram: http://www.chuckschevytruckpages.com/underhoodwiring.html
It is screwed into the top of the engine block right behind the distributor. It is about 3 inches long and laying on it's side with an electrical connector pluged into it. It is hard to get to.
The diagram.
It doesn't have one, it is distributorless.
YES it is.
Standing in front of the vehicle with hood open, looking at the distributor, #1 would be at the 5:00 position on the cap, from there clockwise would be 1, 8, 4, 3, 6, 5, 7, 2.