The issue of "pickup truck brakes" intrigued me, so I went to
www.rockauto.com to investigate. What I found was even more interesting! 12"x3" brakes for B/D-series 1/2 ton pickups, in the middle '80s and back into the middle '70s. The 3/4 ton and such brakes on a 1/2 ton pickup, for many years. ONLY thing was the wheel's bolt circle, in many cases 5x5.5, not 5x4.5 . . . had to go back a few model years to get to the more normal pattern. BUT, in order to put the 12" brakes on anything other than their OEM application, you'd need to know which rear axle they attached to. Obviously the 12" brakes were on a Dana/Spicer axle rather than the normal Chrysler 8.75" axle, I suspect.
BUT going back into the '74 model year, there were 5x4.5 bolt pattern on 11x2.5" Dodge pickup truck brake drums. Not sure why a car 11x2.50 drum would fit, but a pickup truck 22x2.5 drum would not, with the same wheel stud bolt circle specs? Only OTHER thing would be the thickness of the friction material on the brake shoes or perhaps the minimum length of the adjuster mechanisms, both of which might be suspected to be very similar due to the engineering hard points in the design.
NOW, I have nothing against using quality NOS parts, as long as they are available, but that pipeline will dry up at some time in the future. I also know that we've got many generations who grew up with 4-wheel disc brakes on everything. But unless one is in mountainous regions, or other operations where total brake fade can be not-desired, the OEM Chrysler drum brakes served us pretty well, back then, when the main things in brake performance were the friction interfaces between the tires and the pavement AND having the skills to keep them from sliding too much in a panic stop. Which makes an upgraded drum brake system a little better alternative to the aftermarket disc brakes, to me.
Back then, too, my observation was that Chrysler had some of the best drum brake performance of any vehicle, back then. I got spoiled. By comparison, GM brakes would not stop well if they even got close to a mud puddle, until they were dried out! When I upgraded the OEM brakes on my '77 Camaro to the 9C1-COPO Nova police pads (which also spec'd for a Cadillac limo) AND then put the '81 Z/28 Export-spec (and '77-only Monte Carlo) 11x2 rear brakes on it, THEN the brake pedal was near the top AND it stopped "as well as my '66 Chrysler" did. That was back when Wilwood was just doing light-weight brakes for serious drag race cars. BTAIM
So that's where my interests are, just looking to the future. No more, no less.
Enjoy!
CBODY67