So I am looking at purchasing a 1989 Iroc Z with a 5.7 in it. I have done a few searches on here about upgrading the gears in the rear end, it currently has 2.77s.

What is the most cost effect way of upgrading the gears in the rear end to 3.42's? My understanding is I need a 3 series carrier and gears which sounds expensive.

Thanks in advance!

 

find a fourth gen rear end an swap it .

 

4th gen rears are a little wider than 3rd gens

 

You will need a BW 3-series carrier and BW gear sets. Only available ratios are 3:27, 3:45, 3:70 and there may be(???) some 3:73. Only BW 9-bolt parts will work, so forget about anything for a 10-bolt

 

yes they are an inch on each side . but they will bolt right in an work

 

they make 3 series gear sets to fit 2 series carierrs. however, i dont think they make them for 9 bolts? probably gonna be easier to swap rears.

 

Is there any benefit to keeping the 9 bolt? So my best bet is to swap the entire rear for a gear change?

 

More like 2" per side for 93-97 & 1.8" per side for 98+. The stock 16" wheels still fit under the fenders but the 93-97 brakes are the same calipers & rotors as the late model 3rd gens so they aren't an improvement in braking. The 98+ will give you better calipers & bigger rotors, but both will be 10-bolts.

 

You can find a carrier and 370 gears; I did. I even found an extra. The 9 bolt is the better rear. It cost more and that is why they dropped it. The 350 cars and TPI cars got the 9 bolt and the lower end cars got the 10.