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**jocko** · 08-01-2010, 04:43 PM

JGross, here's some pics that might help. These are from the firewall of a 66. In case you can't read the captions on the photos (they were hard to read in Paint) - here it is in a nutshell:

Connector near the heater - is not the heater connection - I believe it's the primary wiring - the wires from the connector come through the firewall into the engine compartment, Tee just behind the vacuum advance canister. One section then goes to the starter solenoid, then the other section goes to coil (+) and also to the temp sender unit on the intake manifold. (the second yellow pointing line points to the heater connection - it's just barely visible at the bottom of your picture - but I'm pointing to it in mine - the rubber grommet with the orange wire coming through it).

As for the other two holes you ask about that are more on the driver's side, they both feed into the rear light harness (you can actually see that they connect (red line) below and the ribbon all goes down the inside of the frame rail to the tail lights.

Bottom line - might want to plan to use the firewall plugs (especially the one near the heater) unless you're rewiring the whole truck in a custom fashion and will have different points of crossing the firewall. If stock wiring, I'd definitely plan to use all of these.

Hope that helps.
Jocko

08-01-2010, 04:43 PM	#2
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,997	Re: help with firewall holes JGross, here's some pics that might help. These are from the firewall of a 66. In case you can't read the captions on the photos (they were hard to read in Paint) - here it is in a nutshell: Connector near the heater - is not the heater connection - I believe it's the primary wiring - the wires from the connector come through the firewall into the engine compartment, Tee just behind the vacuum advance canister. One section then goes to the starter solenoid, then the other section goes to coil (+) and also to the temp sender unit on the intake manifold. (the second yellow pointing line points to the heater connection - it's just barely visible at the bottom of your picture - but I'm pointing to it in mine - the rubber grommet with the orange wire coming through it). As for the other two holes you ask about that are more on the driver's side, they both feed into the rear light harness (you can actually see that they connect (red line) below and the ribbon all goes down the inside of the frame rail to the tail lights. Bottom line - might want to plan to use the firewall plugs (especially the one near the heater) unless you're rewiring the whole truck in a custom fashion and will have different points of crossing the firewall. If stock wiring, I'd definitely plan to use all of these. Hope that helps. Jocko Attached Images Last edited by jocko; 08-01-2010 at 04:46 PM.