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Titan VIB 401

Titan IV Heavy lift with a Centaur-T upper stage. Root part is RC-L01 on the top.
Need 1.8 ver. or higher for the new boosters.
Full fuel LKO payload is about 80t, GKO payload is about 45t, or you can use Centaur-T as an interplanetary engine to transport a light payload to other planet.
Stage is set to be same as the real Titan IVB. 1st stage launch two boosters, be careful in gravity turn because the boosters has only 1° vector and only RC-L01 has reaction wheel. 2nd stage launched when the boosters are nearly burnt out, then launch the 3rd stage to discard them. And you can operate it as the normal rocket (But there's only RC-L01 has reaction wheel, so maybe you need use main engine to turn around).
Remodeling advice:
Adding RCS or reaction wheels to improve the maneuverability.
Also you can decrease the fuel for more realistic experience, such as lauch a Cassni-Huygens mission.