A press release from Aeronautical Engineers, Inc. (AEI) on Feb. 4th, announced that Aloha Air Cargo has selected AEI to convert a passenger 737-300 to a 737-300SF. According to the press release, the 737-300 acquired for conversion is CN 27904 / LN 2691. It was a former Lufthansa 737-330 (D-ABEU) built in 1995. The aircraft is currently in Miami, FL undergoing conversion by Commercial Jet, Inc. and is scheduled to be completed in May 2014. Aloha Air Cargo has not yet released its own press release. 27904 is now registered as N904JW.
Link to the AEI press release
Link to pictures of D-ABEU on airliners.net