[Typpo]

Perhaps the 'L' represents the number of significant iterations of the CAT 4wd platform. For example

A-CAT
B-CAT XL/S
C-ProCAT
D-BossCAT

E-CAT 2000
F-CAT 2000 EC/SE/98
G-CAT 3000

H-CAT SX/2
I-CAT SX3

J-CAT K1/Aero
K-CAT K2

L-CAT L1