timing

i've got a 1994 c 2500 with a 305 in it. i just rebuilt the motor it had blown head gaskets and i pulled the distributor to do so. i read in my manual that i have to pull an electronic spark something or other alittle tan with black line down the side wire. where do i do so. i know it's under the cover on the left hand side but there isnt no tan wire under it.