Assuming we are talking about a V-8, standing in front of the engine #1 would be aprox at the 5 o'clock position. From there clockwise would be 1 8 4 3 6 5 7 2.
Its made inside the distributor.
no
It is right behind the distributor. It is hard to get to and see but it's there.
On the firewall behind the brake pedal
Hard to answer your question when you don't even list which truck and what engine. Look at the link below and pick the correct truck and engine. http://autorepair.about.com/library/firing_orders/bl-gmc-firing-94.htm
It is to the right of the Distributor about 2 inches.
The ignition module is located in the distributor
1987 Sierra classic 2500 GMC Removing spare tire and assembly
It does not have a timing sensor.It has a electronic timing controll module under the distributor cap on the left side of the distributor base plate.
Just put in
Number one is designated by where ever the spark plug wire from the number one cylinder is placed. Number one cylinder is the first cylinder on the the drivers side at the front of the car.
visit the dealer