need your opinion...
 

i have a 350 HO TBI with a t-5. i want to get gears in the rear and im thinkin 3.55's but do u think 3.73's would be too much? its a summer car and most of it will be highway driving, to wildwood and back. what do u think? please help

My 84 had the 305HO T5 with 3:73 and it was great combination. The only down side was that I had edelbrock headers, gutted cat and the flowmaster cat back. So above 70MPH on long hauls the drone in the car made me insane! ( yah it was too loud - but I'm OLD!) could have done a muffler change, but I loved the sound when cruising around town!

you woudl see a little bit of a performance gain with the 3.73's and only cruise about 150rpm higher on the highway.
i woudl go for the 3.73's, actually i would go for 4.10's :D

What gears do you have now? And just so we are clear, you do have a 10 bolt and not a 9 bolt rear, right?

- Justin

it has a stock rear for a 91 305 tbi automatic, but the car has a 350 HO tbi 5-speed in it now, but i dont want to be sitting at high rpms on the highway, well not too high...but i want the car to be quick, so a happy medium would be nice

Well you probably have 2.73s....but you would have to check the RPO codes under the lid of your glovebox to be sure:

GU1 : AXLE REAR, 2.41 RATIO
GU2 : AXLE REAR, 2.73 RATIO
GU4 : AXLE REAR, 3.08 RATIO
GU5 : AXLE REAR, 3.23 RATIO
GU6 : AXLE REAR, 3.42 RATIO
GT4 : AXLE REAR, 3.73 RATIO
GT5 : AXLE REAR, 4.10 RATIO

The 2.41 and 4.10 ratios were not available in thirdgens, but I included them for junkyarding purposes.

- Justin

at highway speeds the difference between 3.73's and 4.10's is only 250-300rpm. that really isn't much at all.

i sent you a pm about the rear i have up for grabs