boeing can be a bit messy, eg: the 737
732=737-200
733=737-300
73Y=737-300F
734=737-400
735=737-500
736=737-600
but.....
73G=737-700 (without winglets) / obviously 737 was a bit ambiguous
73W=737-700 (With winglets)
738=737-800 (without winglets)
73H=737-800 (with winglets)
have not seen the 900 codes yet.
-jd