I have an 85 Firebird which had the stock 2.8L and a 5 speed,but I changed the motor to a 350 carb with a automatic. What types of gear ratios could I have, and will my stock rear end be enough to handle the 350? I was told that the V6 and the V8 cars had the same rear ends. Thanks.

 

Drive down the hiway at 100klm's/hr in "DRIVE", not "OD". Read your V8 tach. Not the V6 tach.
What does your Tach read? What size rear tires do you have? eg(P-225-60-15) I'll tell you what gear you have.
Give me a description of your motor and modifications (intake, carb, cam, heads, exhaust etc), so I can estimate your Horsepower and rpm range. I'll suggest the best gear for 1/4 mile acceleration and what It will rev at 100Klm/Hr. Or I can suggest changes to your motor that will better match your gear ratio. The more detail you tell me the more accurate my recomendations will be.

 

Well, they accept the same gear and carrier, but I think there are differences between the high performance axle housing and the V6. I have one in my basement and it has a thicker cross section in a few areas with the addition of some supporting webs where the cover mounts. Nothing to worry about at the point you are at, though.

They liked to put 3.42's behind the 2.8's with manuals, so check that. Look in your glove box for a white sticker with a grey top. I think there are axle codes printed on that sticker.