On most (if not all) treadle valves available since FMVSS121 went into effect, both brake light switches (for the truck and trailer) run off of the line coming from the secondary chamber of the treadle valve to the quick release valve for the steer axle brakes.
The king pin is part of the trailer, not the truck...
Do it from the inside of the trunk, if I remember correctly, You have to take off the brakelight/turnsignal/backup assembly from bolts found in the trunk, it comes out in 1 large piece. JT
Spark plug gap on a 1979 Ford Truck?
One can view photos of a 1979 Ford truck from many sources online. Some of these online sources include, Ford Cummins, Southern Truck and Race Dezert to view photos of a 1979 Ford truck.
1979 Ford
dexron
in the transmission
A 1979 truck will likely be purchased from a private party. One could try doing a search on eBay Motors or Craigslist to find the desired truck. Also, local classified ads can be a great resource.
with a torque wrench
Check out this site, http://www.nadaguides.com/
yes
Rochester Quadrajet.