IABS

Apogee Kick Stage

The Integrated Apogee Boost Stage (IABS) was built by GE Astro Space (later Lockheed Martin) and powered by two NTO/MMH fueled Marquardt/Aerojet-Rocketdyne R-4D engines. It flew from 1992 to 2003 on Atlas-II and Delta-IV Medium rockets as apogee kick stage, inserting DoD Defense Satellite Communications System (DSCS-3) satellites into geostationary orbit.

Atlas Rocket Family
The Atlas rockets were a Convair development of the SM-65 Atlas missile, which was first tested on December 17, 1957. Having no inherent structural stability, the core sustainer stage needed to be pressurized when vertical.
Thor-Delta Rocket Family
The Thor-Delta family of rockets first launched in 1958 and lofted a multitude of satellites, space probes and spacecraft. It evolved from the PGM-17 Thor IRBM booster into the Delta IV Heavy launch vehicle.
Wikipedia (en)
Gunter D. Krebs, Gunther's Space Page (en)
USA
Aerojet Rocketdyne
General Dynamics
Lockheed Martin
Marquardt
PrimeX
RCA & GE
R Engine