Wiring diagram for 1973 C20 Crew Cab?

[dwmitchell61]

My gal has a 1973 C20 Crew Cab. It originally had the 454ci in it. Someone had swapped that for a 350ci small block engine which is getting tired and the transmission is a goner.

She bought a 1988 Canadian GMC C1500 with a 305ci small block and TH400 heavy duty transmission (maybe a 454 can go back in there in the future).

I am in the process of cleaning out the '88 TBI/engine compartment wiring harness and getting it ready to go into the '73. I am needing to tie into the Park/Neutral switch for the ECM & brake switch for the downshift relay. I also need to tie into the ignition switch "run" lead.

Can anyone supply me with a link to a wiring diagram for the 1973 Chevrolet C20?

Thanks in advance for any help offered...
Dave