Ford 2003 Mustang Workshop Manual page 11

The axle ratio is:
X5 — 3.8L, non-ABS, 3.27 ratio
Z5 — 3.8L, ABS, 3.27 ratio
ME — 4.6L, Mach One, 3.55 ratio
LE — 4.6L, VX, 3.27 ratio
TE — 3.55 locker (with independent rear suspension) — Cobra
Transmission Codes
The transmission code is:
5—Five-speed manual (T5OD/TR3150) — base
B—Six-speed manual (T56), Cobra
K—Five-speed manual (TR3650), GT
U—Four-speed automatic (AODE/4R70W)
Spring Codes