Which gears to use in 12 bolt
I have 68 Impala with 3.55 10 bolt with 26.5in tires. I'm putting a 12 bolt eaton posi, not sure what size gear to put in. It's a street car but I may take it down the track a few times.It has a 550 hp big block with 5 spd tremec .64 overdrive.I'm going to put a 28 in tire on and I'm thinking about going with a 3.90 or 4.10. If I go with the 4.10 and use a 4 series carrier will I be able to go with a 3.90 using the 4 series carrier if the 4.10 is too much.I know they make a 4.10 in 3 0r 4 series carrier but not sure what the real difference is. Thanks for any suggestions.