HELP! need everyones thoughts on 3.9 diff gears!!! urgent

[slappedvr]

hey guys
im getting my new lsd diff installed in a few days and im having a very hard time deciding what diff gears to get.
im tossing up between 3.45s and 3.9s
my car is an automatic vr v6 commodore .
all information and tips would be of great help.(revs at 100kph,shift points)
cheers

 

[vr1uz-fe]

can you get 3.7's

i know my boss has 3.7's in his vz gto but they have a differnt housing

but out of the two options i would go the 3.45's

 

[slappedvr]

to hard to find 3.7s ive tried.
alot of people say 3.45s dont make much difference.

 

[slappedvr]

anyone????

 

[brodiewilson]

do you do much highway driving?

 

[slappedvr]

no not really

 

[brodiewilson]

If you tell me what size tires you have and what rpm it redlines at i will work out your shift points and 100km/h rpms with both ratios.

 

[slappedvr]

215/60/r15
shifts at about 5500rpm

 

[brodiewilson]

with 3.45s it will sit on 2016rpm at 100km/h and shift at 62, 119, 191
with 3.9s it will sit on 2278rpm at 100km/h and shift at 55, 104, 169

 

[slappedvr]

thanks mate that helps alot
also when i get the gears installed
will it stuff up the way my auto shifts?