A (1926): SV/OHV 21-inch single (magneto ignition) 
   A (1960): TS (two stroke) 165CC Topper scooter
   B (1926): SV/OHV 21-inch single
   B (1955): TS 165CC single
   /B: Belt-drive Sturgis model (ex. 1982 FXB)
   C (1920): i.o.e. 35-inch single, special order
   C (1930): SV/OHV 30.5-inch single
   /C: Custom, Classic or Caf
   /CH: Magneto Sportster (ex. 1958 XLCH)
   D (1929): SV 45-inch twin
   /D: 74-inch engine (ex. 1921 JD)
   /D: Extra power (ex. 1930 DLD)
   /D: Dyna Glide frame (ex. 1991 FXDB)
   /DG: Disc Glide (ex. 1983 FXDG)
   E (1936): OHV 61-inch twin
   /E: Electric starting (ex. 1964 GE, 1974 FXE)
   /E: Police engine (ex. 1953 FLE)
   F (1920): i.o.e. 61-inch magneto ignition (dating from 1914)
   F (1941): OHV 74-inch twin
   /F: Battery ignition flat twin (ex. 1921 WF)
   /F: Footshift (ex. 1952 FLF)
   G (1933): SV 45-inch Servi-Car
   /H: Larger engine (ex. 1936 80-inch VHL, 1955 55-inch
   KH)
   /H: More powerful engine (ex. 1955 FLH)
   I: Fuel injection (ex. 1995 FLHTCI)
   J (1920): i.o.e. 61-inch twin (dating from 1915)
   /J: Magneto ignition flat twin (ex. 1921 WJ)
   /K: More powerful K model (ex. 1955 K11K)
   L (1920): Single-passenger sidecar (dating from 1915)
   /L: Higher compression engine (ex. 1936 EL)
   M (1920): Commerical sidecar (dating from 1915)
   M (1965): TS 50CC single, Aermacchi
   /N: Newspaper delivery sidecar (ex. 1929 MN)
   /N: Nostalgia (ex. 1993 FLSTN)
   /O: Open-body commercial sidecar (ex. 1926 MO)
   /P: Police model
   Q (1920): Two-passenger sidecar chassis (dating from 1918)
   R (1932): SV 45-inch twin
   /R: Rubber-mount FX model (ex. 1982 FXR Super Glide)
   /R: Pseudo-racing model (ex. 1983 XR-1000)
   /R: Racing model (ex. 1952 KR)
   S (1926): OHV 21-inch, for racing purposes
   S (1948): TS 125 single
   /S: Sport (ex. 1978 FXS and XLS)
   /S: Sidecar use (ex. 1936 ES)
   T (1921): Twin-cylinder racer
   /T: TS 165 single (ex. 1953 ST)
   /T: Touring (ex. 1977 XLT, 1980)
   U (1937): SV 74-inch twin
   V (1930): SV 74-inch twin
   V (1994): DOHC 61-inch twin, for Superbike racing
   W (1920): SV 36-inch flat twin (dating from 1919)
   W (1937): SV 45-inch twin
   /WG: Wide Glide (ex. 1980 FXWG)
   X (1957): OHV 55-inch twin (usually used with L; i.e. XL)
   /X (1971): Lighter, Sportster-type front end
   Y: Only letter never used
   Z (1973): TS 90CC single, Aermacchi