What Rocket Am I?: Quiz 21

Clue 1: I stand 31 meters tall.
Clue 2: I powered the Gemini spacecraft missions.
Clue 3: I was first used for orbital launch in 1964.
Clue 4: I was developed by Martin Marietta for the United States Air Force.
Clue 5: I am an ICBM adapted for manned orbital flights.
Clue 6: My payload to low Earth orbit is 3,600 kg.
Clue 7: I use hypergolic fuels for storable propellant.

Yes, I am Titan II.

I enabled NASA's first spacewalks during Gemini.