These no air, pressure bled, rears adjusted to slight drag, never heard of twin leading shoe rear brakes, don’t know what that is.
MY MISTAKE, and I've edited the post to correct it. What I originally called "Twin Leading Shoe" rear brakes are in fact "
Leading/Trailing Shoe" rear brakes.
What doesn't change is that THEY SUCK.
So far as I know, the Leading/Trailing Shoe brakes are used only on the 1500s. Even 6-lug 2500s had duo-servo rear brakes. I know this because I took off the 10-bolt 8.5 ring gear axle from my '88 and replaced it with a six-lug 14-bolt 9.5 semi-float axle from a 2500, and got the better duo-servo brakes in the process along with the heavier axle.
Leading/Trailing shoe brakes use IDENTICAL SHOES, and the adjuster mechanism is ABOVE THE AXLE SHAFT. The bottom of the shoes rest on a solid, fixed "block" attached to the backing plate. They adjust as I said--set the park brake, release the park brake, press on the regular brake pedal. (repeat a hundred times.)
The more-familiar DUO-SERVO brakes have primary shoes and secondary shoes, the primary is typically lighter-colored friction material that's thicker, softer, and shorter than the darker-colored material on the secondary shoe. The adjuster is a "floating" link (threaded, with a star-wheel) between the shoes at the BOTTOM (where the solid "block" would be on Leading/Trailing Shoe brakes.) They self adjust by braking firmly in reverse. It's a totally-different mechanism.
Pressure-bled means nothing in terms of "no air" on any vehicle with an anti-lock system or a vehicle where the master cylinder is tipped "up" in front. Both the anti-lock and the master cylinder can trap air that WILL NOT BLEED OUT via the wheel cylinders.
On my '88, the RWAL has it's own bleeder screw. I had a crappy, low, squishy pedal until I burped the ABS.
Sometimes a master cylinder must be tipped so that it's level--or even slightly down in front--to remove the last of the air through the compensating port(s) between the master and the reservoir. This may be done by jacking-up the rear of the vehicle to level the master, or by removing the master from the firewall or booster WITHOUT DISCONNECTING THE METAL TUBES, and just forcing the master down in front--then touch the brake pedal (vehicle raised in back) or tickle the primary piston with a Phillips screwdriver or wood dowel (Master disconnected from booster) until the bubbles transfer from the cylinder to the reservoir.