What is the timing setting for a 1992 Chevy 2500 350 auto w air and what if any wire do you have to unhook from the distributer?

1992 Chevy 350, you need to unplug the brown wire under the black cover on the pass side firewall. Then make sure its timed on 0 measured at the front of the damper. If it does not run right take off the dist cap and with a socket and long breaker bar have someone watch the dist rotor as you turn the engine reverse rotation, what you are looking for is a slack in the timing chain. If their is significant slop, then retime engine 2 degrees advanced til it is running good again. When you are done reconnect the brown wire and put the plastic cover back on. Done.