Big & loud. I remember them well. A couple used to land at Kelly AFB. I cannot remember if they were stationed there.
The Air Force Reserve "schoolhouse" unit for the C-5 is at Kelly Field/Lackland AFB, and has been for a long time. Kelly AFB is gone, but Kelly Field is now part of Lackland AFB. They just moved the boundary between the two to the east side of the airfield, before they turned the base into Kelly USA industrial park. They still overhaul airplanes and engines there, but it's all contractor now.