Abreviaturas para los modelos
FXS softail
FLS fatboy
FX dynas
FLT ultras
FLH RoadKings electra y algunas Ultra

Hay un chingo de combinaciones pero a groso modo así es

si existe una razon en la designacion de esas letras, te paso el texto en ingles tal cual esta en las paginas de Chop Cult.

FIRST LETTER–ENGINE DESIGNATIONS:
G: Servicar three wheeler, 1937 to 1972
E: Overhead valve 61 cubic inch Big Twin (separate motor and transmission)
F:  Overhead valve 74, 80 or 88 cubic inch Big Twin
FL: 80 to 88 cubic inches and a fat front tire (a.k.a. 74" 1941 to ‘82)
K: Side valve 45 and 55 cubic inch sports bike that replaced the WL in 1953, and was replaced by the Sportster in 1957
U: Side valve 74 or 80 cubic inch Big Twin
V : Side valve 74 cubic inch 1930 to ‘36. (Also 1935 to ‘36 VLH; VHS in 1980)
W : Side valve 45 cubic inch from 1937 to 1952
X: Sports and special construction. Applied to 1918-1922 opposed twin
    Sport, 1944 military opposed twin, and Sportsters 1957 to present

SECOND LETTER–FRONT END DESIGNATIONS (except XL Sportsters):
X: Narrow tire and sport fork
L: Wide front tire and Hydra Glide fork

THIRD LETTER–FRAME STYLE DESIGNATION:
D: Dyna frame with the rubber mounted motor
HT: Highway Touring frame
ST: Softail

REMAINING LETTERS–SPECIFIC MODEL WITHIN FRAME CATEGORY:
A: Army (military) version, except GA (Servicar without tow bar)
B: Battery start (early models); Belt drive (early ‘80s); Black paint (‘95-’96 model, the Bad Boy)
C: Classic, Competition, Custom and various other meanings
Dyna: newest current Big Twin frame and engine mount design
DG: Disc Glide
E: Electric start
F: Foot shift (when the standard was hand-shift) and now "Fat Boy"G: Servicar
H: High Performance, Hand shift or Heavy Duty, depending on model and era
I: Fuel Injection
L- Big fat front tire
N: Nightster
LR: Low Rider, alhough many Low Riders don't include “LR” in the model ID
N: Nostalgia
P: Police version
R: Rubber-mounted or Race, depending on model
ST: Softail
S: Springer
S (without following T): Sports version
T: Touring
WG: Wide Glide
X: Sportster or Sportster-style narrow front fork with 21” front wheel/narrow tire

SPORTSTER ABBREVIATION ENTYMOLOGY:
X: Sportsters; direct descendent of K series, 1952 to ‘56
XL: Started in 1957; unit construction engine/transmission
L: High compression (7.5:1 in 1957)
H: Starting in 1958; Higher-power, High-compression or Hot
C: Also added in 1958, as in XLCH, for Competition
CR: Cafe racer style, with bikini fairing
LT: Touring with bigger tank, thicker seat, hard bags

@Walo al servicio de la comunida'!!! Jajaja saludos canijo!!!