first i must thank everyone for all the help, its saved me alot of money time and swearing and damaging my beater car out of anger. i have the stock rear end in my 86 trans am and i no ill need to replace it sooner or later since im in the process of getting the lt-1 running in it, i would like to get a 9 inch or 12 bolt for it but my wallet cant handle that so im hoping to replace the gears and possibly the cover. the thing is im not sure what to go with im thinkin 4.11s but im not sure. behind the 300hp 5700 rpm redline engine i got a 94 t-56 that as far as i no has got gearing of
1st-2.66
2nd-1.78
3rd-1.30
4th-1.00
5th-.74
6th-.50
with 26 inch street tires
and used 27 inch dirt track slicks for the track
i no plenty of people out there have already done this swap and i was hoping to get some opions of what gearing might work good for me. once i get it going im planin on it just being my weekend warrior that i cruise around in and occasionaly take to the dragstrip. itll be a mix of city, country a lil highway driving and if its anything like before i wont be that easy on her so im hoping for something that can get up and go, have a good speed capability, and not kill me on gas. im also asking because i no the old 305 t-5 could cruise at 40 at 1200rpm good and 125 at 3200 and the gas was always decient but i dont no at what kind of rpm's the lt-1's run good at since i havnt drove it yet

 

I'm assuming you have the 10 bolt in it currently. Anywho if you run slicks on it with 300rwhp it will more than likely detonate the first time they grab.

I would say keep the gears you have now and drive it and if it isn't any fun use a gearing calculator to find out the best all around gear for it.

That's what I did when I had a t56 and a 2.77 rear end.
Of course I still have the long runner tpi and I burn through my power band so fast that I'm only competitive with stock 305's, but that will be fixed next.

 

try the Dana 60. the whole rear end is stronger than the 12 bolt and eats up less power. Price is also fair at about $2,200 if you look. I have heard of T56 with 4.11 that ran under 2K rpm. I would say 3.73 or 3.42 if you want a daily driver.

 

the dana 60 is also heavy as hell and you have to shorten your driveshaft

 

The Dana 60 eats WAY MORE power than a 12 bolt or even a 9inch !!!
GM High Tech just did a compar o on them..

 

Strange 12 bolt eats up the least power and comes standard with 33 spline axles, and costs 1922 at spohn

 

was just saying it's price is pretty good a nine blot when it is all said and done is super expensive and the dana 60 is stronger than a 12 bolt. Ya you need a custom driveshaft but that is never a waste of money.

and ya i got the facts mixed up for a sec. the 60 does eat more power. And yes it may be heavier but it's also stronger. For me it was all about budget vs. what i'm getting.

 

Under 2000rpm? When? Mines a dd and I'm very happy with the 4.11's.

 

Not may people use this gear set but I'd go with a 3.9x if it's available.