1956 GMC AD

Text from ad above.
"The Torture trail"-a block-studded stretch at the GM Proving Ground. The first vehicle has standard springs and shock asborbers-and see it bounce! The second has added RSD Suspension. Note its smooth passage at the same speed! These oscillographs tell the story.

We call RSD Suspension-
you'll call it a miracle!

EVERY ONCE in a blue moon there comes an engineering advance so sensational that it leaves the rest of the automotive industry far behind. Today, GMC brings you another-on our improved Blue Chip half-ton models.
It is RSD Front-End Suspension which means that the front wheels-in addition to regular springs and shock absorbers that lessen jolts-are equipped with an amazing new device known as a Road Shock Damper* that eliminates wheel bounce on the roughest roads.
The result is a ride so incredibly comfortable you can hardly believe it. A Blue Chip GMC pickup with RSD Suspension rides-not merely equal to a passenger car-but with a miraculous smoothness never known before in any wheeled vehicle!
No longer need you slow down for rough going. Vehicle slewing is eliminated. Steering is easier-driver fatigue greatly reduced. Even delicate produce is protected from damage. Believe it or not, you won't even feel tramp over the expansion joints in concrete pavements!
Prove it to yourself: let your GMC dealer give you a demonstration ride with RSD Suspension. Pick the most viciously stubbled road you know. Then see for yourself how RSD Suspension seems to repave it as you sail over it! Make that date today.
GMC TRUCK & COACH-A General Motors Division

How RSD Works! The Road Shock Damper applies in reverse an age-old physical law which explains how the rhythmic steps of marching men can set a large suspension bridge into dangerous motion. In the Road Shock Damper attached to each front wheel the weight "W" floating on springs is" is harmonically tuned to the natural frequency of the vehicle's unsprung weight. Its harmonic oscillation acts as a dynamic brake and reduces wheel-hop to a mere flutter.

New 180-H.P. V8 and 140-H.P. six engines with the largest displacement in the industry - New options include fast-cruising axle ratio-and Safety Power Steering - New Kudu Stabilizer - Tubeless tires and 12-volt electrical systems are standard equipment.
*Standard on the Suburban; optional at slight extra cost on other 1/2-ton models;

GMC Emblem