Standing in front of the truck looking at the distributor, #1 would be at the 7 O'Clock position on the cap, from there clockwise it is 1, 2, 3, 4, 5, 6.
165432 is the firing order for the 4.3 L engine
The firing order on the 2.5L 4 cylinder engine is: 1 3 4 2
18436572
Firing Order
if your asking if that is the firing order yes it is
18436572
Most Chevy v-8's have the firing order of: 1 8 4 3 6 5 7 2
1.6.5.4.3.2
If you have a 305 or 350, it is 1,8,4,3,6,5,7,2.
Firing order is 1 2 3 4 5 6.
try www.haynes.com
The firing order for the 2.5L engine is: 1-3-4-2