The Saturn MLV was a proposed concept family of rockets, intended as a follow-on to the Saturn V. MLV stands for "Modified Launch Vehicle".
Vehicle configurations representative of several alternative uprating methods were specified by the Marshall Space Flight Center for initial studies.
The baseline Saturn MLV would incorporate these changes from the Saturn V vehicle. Saturn IC (first stage) stretched 240 inches with 5.6 million pounds propellant and 5 new F-1A engines; S-II (second stage) stretched 41 inches with 1.0 million pounds propellant and 5 J-2 engines; S-IVB (third stage) strengthened, but with standard 230,000 lbs propellant, 1 J-2 engine.
*) Indicates zero stage strap on boosters. In both cases 4x-Titan UA-1205