How do you set the timing on a 1994 GMC 4x4 truck .Got lost on the bypass the ign. part?

I will try to save you all the time i wasted looking for where they hid the disconnect and get right to it. There are 2 plugs on the back of the distributor. One has a light tan with black stripe wire in with the rest of them. Try to get enough slack in the wires to cut just that one. Then splice in a piece of 18 gauge wire with it's own single plug. Plug the main plug back in, and leave the tan/black wire unplugged. Set your timing to zero degrees, then plug the tan/black wire in. The tan/black wire isolates the engine computer when unplugged so you can set the base timing at zero. When you plug it back in the computer takes over the timing to adjust for rpm,vacuum,and all the assorted functions that we didn't need computers for when i was growing up. Have a nice day.