Technical : The Axle Code

source:

http://www.supramania.com/forums/showthread.php?70721-Toyota-Axle-Codes&highlight=ring+pinion+ratios

for toyota model only, check the tag on the firewall

Axle Codes:
First Digit = Ring Gear Diameter
A=138mm
B=145mm
C=6.25"
D=6.62"
E=7.1"
F=7.5" ('82-'86 A6 chassis)
G=8" ('86.5-'92 A7 chassis)
H=9"
J=9.25"
K=9.5"
L=10.5"
M=12.5"
N=13.5"
P=14"
R=162mm
S=6.38"
T=6.7"
U=6"
V=10.6"
W=15.5"
X=142mm
Y=158mm

Second and third digits = Gear Ratio

01=3.30
02=3.36
03=3.545
04=3.556
05=3.70
06=3.889
07=3.90
08=4.111
09=4.222
10=4.375
11=4.444
12=4.625
13=4.79
14=4.875
15=5.125
16=5.286
17=5.60
18=5.714
19=5.833
20=6.167
21=6.667
22=6.78
23=6.833
24=7.64
25=4.556
26=5.571
27=3.364
28=4.300 (MA70 NA)
29=4.100 (JZA70)
30=3.727 (Late '89+ MA70 Turbo)
31=3.909 ('87-'89 MA70 Turbo)
32=6.591 OR 5.583
33=7.503 OR 5.583
34=6.781 OR 4.786
35=7.636 OR 5.600
36=4.778
37=3.583
38=3.417

Fourth Digit (number of pinion gears / LSD or Open)

2=2 Pinions Open
3=2 Pinions LSD
4=4 Pinions Open
5=4 Pinions LSD

since i haven't change to Independent Rear Suspension or IRS yet, the axle code on my car is F282...no wonder the respond feel great,the ratio is 4.3...fuh deng hehe...