The S-300PS/S-300PM (Russian "С-300ПC"/"С-300ПМ", NATO reporting name "SA-10d/e") was introduced in 1985 and is the only version thought to have been fitted with a nuclear warhead. This model saw the introduction of the modern TEL and mobile radar and command-post vehicles that were all based on the MAZ-7910 8 × 8 truck. This model also featured the new 5V55R missiles which increased maximum engagement range to and introduced a terminal semi-active radar homing (SARH) guidance mode. The surveillance radar of these systems was designated 30N6. Also introduced with this version was the distinction between self-propelled and towed TELs. The towed TEL is designated 5P85T. Mobile TELs were the 5P85S and 5P85D. The 5P85D was a "slave" TEL, being controlled by a 5P85S "master" TEL. The "master" TEL is identifiable thanks to the large equipment container behind the cabin; in the "slave" TEL this area is not enclosed and is used for cable or spare tyre storage.