A partial explanation from a couple of year ago:
Harley Davidson Motorcycle model and designator letters are explained below:
DYNA Glide - FX - Superglide, FXB - Sturgis Belt, FXD - Dyna Super Glide, FXDG - Dyna Glide/Sturgis, FXDL - Dyna Low Rider, FXDS-CON - Dyna Convertible, FXDWG - Dyna Wide Glide, FXDC/I - Dyna Super Glide Custom - fuel Injected, FXDX - Dyna Super Glide Sport, FXDXT - Super Glide "T" Sport, FXE - Superglide Electric Start, FXEF - Fatbob, FXLR - FX Lower Rider - Evolution,
FXR - Rubber Mount Super Glide - FXRDG - Disc Glide, FXRP - Police or pursuit, FXRS - FXR Sport, FXRS-CON - FXR Sport Convertible, FXRS-SP - Low Rider Sport Edition, FXRT - FXR Touring, FXS - Low Rider/Shovelhead, FXSB - Low Rider Belt,
Softail - FXST - Softail Standard, FXSTB - Night Train, FXSTBI - Night Train fuel injected, FXSTC - Softail Custom, FXSTD - Softail Deuce, FXSTS - Springer Softail, FLST - Heritage Softail, FLSTC - Heritage Softail Classic, FLSTF - Fat Boy, FLSTN - Nostalgia, FLSTS - Heritage Springer Softail.
Touring FL - FLH - 4-Speed Dresser, FLHS - 4-Speed Electra Glide, FLT with windshield and less goodies S = Sport, FLHR - Road King. FLHRCI - Road King Classic, FLHS- Electra Glide Sport, FLHT - Electra Glide Standard, FLHTC - Electra Glide Classic, FLHTCUI - Electra Glide Ultra Classic, FLT- Rubber Mount Dresser , FLTC - Rubber Mount Dresser Classic, FLTCU - Rubber Mount Dresser Classic Ultra, FLTR - Road Glide, FLTRI - Road Glide w/ Genuine Access, FLTRSEI - Screamin Eagle Road Glide,
VRSC - (V-TWIN Racing Street Custom) , VRSCA: 1st model of the V-ROD family.
Sportsters - XL - 4-Speed Sportster, XL883 - Sportster Hugger, XL883C - Sportster 883 Custom, XL1100 - Sportster 1100, XL1200 - Sportster 1200, XL1200C - Sportster 1200 Custom, XL1200S - Sportster 1200 Sport, XLCH - 4-Speed Sportster, Kick start, XLCR - Cafe Racer 1000, XLH - 4-Speed Sportster, Electric Start, XLH883 - 883 Hugger, XLH1200 - 1200, XLH1200S - Sport, XLS - 4-Speed Sportster Roadster, XLX - 4-Speed 1000cc Ironhead, XR1000 - XLH with XLR Heads.
X - Sportsters. These descend from the K series, 1952-56
XL- Series started in 1957. They are "unit construction" (engine & transmission share a common case)
L - High compression (7.5:1 in 1957)
H - Starting in 1958 came the XLH, meaning Higher-power or High-compression (9:1) or Hot .
C - Also in 1958 was the XLCH. The C was intended to mean "Competition".
CR- Cafe racer style, with bikini fairing.