you can also look on the sticker on the drivers door for the axle code. pretty sure the codes for 4.10 are 42=4.10 open and 4d=4.10 lsd. i have posted the code chart on here before i believe
edit: i found it
43 Open 3.08
41 Open 3.27
42 Open 4.10
46 Open 3.73
45 Open 3.55
D4 Limited Slip 3.73
D2 Limited Slip 4.10
L73 Limited Slip 3.73