Although several variants were put forward, only the Delta 4925 was launched.

The designations used a four digit numerical code to store information on the configuration of the rocket.

It was built from a combination of spare parts left over from earlier Delta rockets, which were being retired, and parts from the Delta II 6000-series, which was just entering service.

The first stage was the MB-3-III powered Extended Long Tank Thor, previously flown on the 1000-series.

A Star-48B PAM-D was used as a third stage, to boost payloads into geosynchronous transfer orbit.