First, Dyna is NOT a Softail. Where is "XTC" on it? The rest of your supplied numbers in order mean; 1 = made for USA sale, HD = obvious, 1 = heavyweight over 901 cc, B = FX line, K = softail, L = evolution 80 ci engine, 1 = regular introduction (not a special midyear change) 4 = check digit, a number that must match other parts of the serial number, based on a mathmatical formula. The next two letters (not supplied) are the model year and assembly plant. The last numbers (not supplied) are the sequential production numbers.