Just looking for some info from someone who has this setup. I have a leaky pinion seal on my 99ta, and I am thinking that when I rip the rearend apart I would like to put new bearings and new 4:10 gears in it. What kind of RPM can I expect with the T56 with 4:10 gears at 75 mph. That is the biggest question I have about it. I know it will make it a lot quicker, but I don't want to sacrafice the driveability of the car.

 

most say first gear is useless, and street tires can't take it
www.f-body.com/gears i think is the website where it'll tell you rpms at each speed
and my personal suggestion, go with 4.11s made by motive/gm
they don't whine and are a lot stronger than 4.10s (they are 9 and 37, whereas 4.10s are 41 and 10)

edit- this also belongs in the drivetrain section

 

2000 rpms @ 74-75 mph

 

that link isn't working use this one

 

First gear will be useless; I ran them for 40K miles and switched to 3.50 gears when I installed my 9".

 

Thanks for the info guys. I think I am going to do 4:10's. I can't really justify going with a 3:73 because I already have 3:42's. I know 1st gear will be uselsess, but I think it will make up for itself in fun.

 

i was wanting to put 4:11 gears in my t56 as well,
i'm not sure what i'll be trapping (forged 355 + occasional n20)
somewhere around 115 - 125 mph, will i be in 5th gear when i cross the 1/4 mile? i really don't want a 4-5 shift while racing..
-Jason
if i remember right, i was traping 103 in 4th gear on stock 3:42 gears..

 

Where do u find 4:11's by motive for 7.5" rear? all i can find is the 4:10's

 

i get just under 2k at 75 and i can break 30 mpg on the highway. you wont be disappointed with 4.10s

 

i think most sites list them as 4.10s but you should call and make sure that they are 4.11s