cybertiger130

I am replacing my 305 with an 350 LT1, automatic, it has a stock 273.
I want to replace it with a 323 or 342.
This is just a street car ( Maybe a little street drag on and then).
I read a post that a t-top car flexing under power, I dont even know if this will be an issue.
I just want to know which rear gear is best.

Thanks Michael

thirdgenlover

might as well go with the 3.42 if those are the only ones that you have under consideration. 3.23 to 3.42 wont be able to tell much of a difference. i have 3.73 in mine and i had 2.73 too, going from it to 3.73, big difference. not much sacrifice in it either. at 60 mph, im just a hair above 2000. if its between 3.23 and 3.42, might as well go 3.42

rik89gta

The t tops flexing shouldnt be deemed as too much of an issue unless Your making 400+ horspower at the very least. If Your gears are stock in an 89, I highly doubt that they were a 2.92 ratio. That was never a stock ratio at all! If you have a 10 bolt axle,,,Your ratio is probably either a 2.73 to a 3.23 at the highest. Although in 89 most came with a 9 bolt axle,,, which usually came with either a 2.77 or 3.27 for an automatic trans at the highest. But if your car originally came with a 5 speed, You most likely have a 3.45 ratio with a 9 bolt axle. So count Your bolts on the axle, read Your RPO sticker codes and let me know what You have. A stock cammed LT1 also doesnt respond dramatically to significant gear ratio changes. I've read about many people that have swapped from a 3.23 to 3.73, and they gain absolutely no ET in the quarter mile at the expense of their gears howling, and a decrease in gas mileage. But if Your car has 2.73's... It's definitely worth throwing 3.42's or bigger in there....

rik89gta

I just noticed that You edited Your thread, and the 2.92 was obviously a mistype. But I would go with the 3.42's if Your running an automatic trans. The 3.42's are a perfect matched gear for an automatic LT1 car. The 3.73's will rev Your engine to the redline a little quicker but I dont think they are worth the decrease in gas mileage. Let alone the obnoxious howling that typically comes from any numerically higher gear ratio...

cybertiger130

First of all thanks to all the people that replyed to my first post.
I looked up the build code list that came with the car.
First code is GU2 Axle gear is a 2.73 ratio.
Second is G80 Axle Positraction, Limited Slip.
Now should I replace the whole thing or just the gear & pinnion .
If the latter what do you put in it.
Thanks Michael

rik89gta

I would just replace the ring and pinion. Leave the posi alone unless there is something wrong with it. The best gear for a stock cammed LT1 is probably the 3.42. You could go 3.73, but it might not be worth the waste of gas and the noise that comes with it.