yes, that was Space tug concept for NASA in early 1970s
The Idea was the Space shuttle or Saturn V bring the Tug in orbit do it mission, get refuel and new payload.
return after two years in orbit get refurnish and launch again.
NASA wanted to use the Space Tug for various Mission types
launch satellite to GEO or Space Probes to destination
reboost Satellite and space station in orbit or retrieve satellite to Space Station.
manned flight for satellite repair or flight into GEO or Moon orbit
or serve as Ferry between Moon orbit and it's surface.
off course that kind of mission demand highly complex design, what let to modular approach by most companies like Boeing
there version had some problems like putting the Crew module on top
what need a very long ladder for astronauts
while Rockwell put the Crew pod and engine landing gear under fuel tank what simplified the EVA
The Space tug concept was gradually abandon in favor of a unmanned stage, in end it became disposable Centaur stage for Shuttle after 1973