'82 step van wiring diagram?

[jimfulco]

Anybody know where I can look at a wiring diagram for a 1982 1-ton step van (P30)? Or something similar? I need to get the turn signals working, & it's got some kind of aftermarket turn signal switch that clamps to the column, an OEM switch under the steering wheel, & all the wires to both have been cut. It has an intact (seemingly) flat connector under the dash, but all the faded pretty colors have me confused.