Steve Ketteridge's side left West London with their heads held high after a gutsy showing despite their brave FA Cup run begin finally ended by Premiership side QPR in a game switched to Loftus Road.
Rangers opened their account in the 10th minute when Ducks keeper Paul O'Reilly failed to cut out Michael Meaker's corner and Danny Maddix glanced his header in off a post.
Then, two minutes later, Rangers defender David Bardsley was yellow carded by Loughborough referee Peter Jones after clattering into Lennie Brayshaw who was forced off the field for a while to have nine stitches in a head wound.
Simon Barker wasted a great chance for Rangers when he fired over from 20 yards in the 20th minute after being set up by Kevin Gallen before, with United still a man down, Rangers doubled their lead in the 26th minute. Les Ferdinand combined well with Clive Wilson on the left before making space for Meaker to run at the defence and his pass infield found the on-running Ferdinand who rounded O'Reilly to slot home.
In the 36th minute United had their first chance of note when Lee Harvey's throw was laid off by Mickey Danzey to Steve Heard whose 20 yarder was well saved down to his left by Rangers keeper Tony Roberts.
The third goal came in the 40th minute when Ferdinand robbed Harvey to leave himself clear on goal but despite O'Reilly forcing him wide, the England international doubled back to pick out Gallen in the middle to score.
The last major chance of the first half came two minutes later when O'Reilly got down well to make a fine save from Ferdinand's header after Meaker's corner.
With the game well and truly beyond the Ducks, it was a case of damage limitation for the second half and in the 71st minute Rangers sub Bradley Allen's angled pass put Andrew Impey through but O'Reilly dived to save at his feet. Four minutes late Meaker's corner led to a goalmouth scramble before a close range shot from Simon Barker was cleared off the line.
The somewhat inevitable fourth goal finally came in the 78th minute when Allen's shot deflected off Ferdinand to the unmarked Meaker in the box and he steered his shot past O'Reilly from 12 yards.
Two minutes later Ferdinand sidestepped United last man Mickey Barnes before having his fierce shot from the edge of the box superbly saved by O'Reilly.
The United players didn't ease up until the last ball had been kicked and despite being well beaten (but certainly not disgraced), manager Steve Ketteridge could be justifiably proud of not only their performance on the day but his side's achievement of reaching the 3rd Round Proper for the first time in Aylesbury's history.
