My f-850 all wheel drive truck has vacuum advanced brakes. On the inside of the left frame rail theres a block that has the brake light switch screwed into it; however the previous owner cut the wires. There are two (2) wires that come off the switch, my question is does one of the wires have constant power and one wire goes to the brake lights?? To dig a bit deeper if anyone can tell me what the factory color the wires would be that would be awesome. My wireing schematic does not show any trucks with vacuum advanced brakes on it. Thanks

 

I asked a moderator to move your thread to the Large Truck forum.

4WD wasn't available in 1968, so it's a conversion.

 

It may as well be. You would know better than i. It has a marmon herrington front en

 

It may as well be. You would know better than i. It has a marmon herrington front end

 

One wire comes from the fuse block, and the other should go to the steering column.. May have been changed by marmon herrington?

 

Will rear brakes from a 1972 f600 fit 1968 f850 ?

 

Doubtful. I would expect the F850 to have a larger axle with a higher load rating and to have larger brakes.

If you have the axle codes you may be able to find out what size brakes were available on each axle. Or, get out the tape measure....

 

Look at column right under F-N850 for rear brake sizes.