The main propulsion system, OK-700A, consists of two pressurized water reactor VM-4S (2×90 MW) with two steam turbines giving 60,000 shaft horsepower (45,000 kW) to two five-bladed, fixed-pitch shrouded propellers with improved hydro-acoustic characteristics.

The Delta III class are fitted with a new sonar system, the MGK-400 Rubikon (in submarine K-424, the older MGK-100 Kerch was installed), developed under the leadership of main designer S.M.

The Delta III class are equipped with a new battle management system, the Almaz-BDR (or MVU-JZBDR) torpedo fire control.

For improved stealthiness, a new inertial navigation system, Tobol-M-1 (on newer ships Tobol-M-2), with higher accuracy, was installed.

The Delta III class includes the Molnija-M communications system, with satellite capabilities provided by the Tsunami subsystem.

In February 1973, State Rocket Center Makayev began development of a new two-stage liquid-fueled ballistic missile R-29R (3M40, RSM-50, SS-N-18).

Improvements in the R-29R over the original R-29 include MIRVed capability and upgraded inertial navigation system with satellite-assisted navigation, giving the new missile greater accuracy (~900 m (3,000 ft)), increasing its damage potential against all types of military targets whether "soft" or "hard".

Fire control for the R-29R is achieved through the D-9R ballistic missile system, which contains sixteen SLBM tubes, just like the preceding Project 667BD.

Only the newest submarine, K-44 Ryazan, had a second general overhaul and refuelling during 2005–2007, which gave it a potential service life to 2017.

[8] As part of Russia's "Thunder 2019" military exercise, Ryazan attempted to launch two R-29R ballistic missiles on 17 October 2019.