Located 11 miles from Muddy Station and 12 miles from Bear River Station. A Quaking Aspen grove and spring are south of the station site. 

http://www.expeditionutah.com/featured-trails/pony-express-trail/wyoming-pony-express-stations/

Quaking Aspen or Quaking Asp Springs has been identified as a station in a few sources, probably because it is listed on the 1861 Overland Mail Company contract.  The Settles mention Quaking Asp, but do not specifically identify it as a station.  Most sources place the site between Muddy Creek and Bear River Stations, but for some unknown reason, Roy Bloss identifies Quaking Asp Creek between Horse Creek and South Pass.

http://www.nps.gov/parkhistory/online_books/poex/hrs/hrs6a.htm#94