Hi folks. I just picked up an 80 stepside with manual disc brakes. It needs to be upgraded. What will I need to switch to power? Thanks

booster and master cylinder.

and a steady vacuum source, from the carb or throttle body.

My buddy insists I need a different proportioning valve for power brakes. I don't see it. What say ye?

The propotioning valve is not affected by the power booster. What was changed is the pedal ratio/ motion ratio. Without any change to that ratio/ with what you have and a booster your brakes MAY be very light, too easily locked.

Get a brake pedal from a power brake equipped truck.

OK, so now I know what I need, what years fit? A local bone yard has an 86 W/power brakes and he thinks they are the same. I do too, but I'm not sure. Any thoughts?

There are a couple different diameters (to clear 440s) and somewhere along the way, Mopar changed the number of bolts that hold the master to the booster. As a unit, I suspect they will bolt up from 73 through 93. If your junk yard buying, its best to pull everything out of the same truck, booster, master, brake pedal, & linkage. I would get the two brake line fittings for the master as well, some are different. Then as long as you know what year the donner truck was, you can get replacement parts for it, whenever you might need them. Gene