hey guys i have an 89 formula with a 5-speed and a 350 makin liek 350 horse and now i have a 9-bolt with 3:27 gears and i need somtin more. i was plannin on goin with 3:73 but my dad talked to some mechanic with a firebird and he said he just took his 3:73's out and got a rear with 3:42's and said he runs better times with them cause he hooks better and its just a better gear. now he has an auto and i have a 5-speed so do u think 3:42's would be a good gear for me? i'm not gonna be at the track everday but i wunt somthing that will make a diff from wut i have now and get me into my powerrange a bit quicker. also i can get a rear out of the junk yeard for lik 250 already with 3:42's so it woudl be way cheasper then getting 3:73's and havin them installed. thanks for your input man

 

since you have a 5 speed anyone one of them will be better than 3.27 that are more on the automatic thirdgens

if you can get a 3.42 posi rear end for 250 then go for it..

 

You want to match your rear gears to your cam's power band. I wouldn't waste money on a 3:42 rear if you already have 3:27s, the gains will be minimal.

Now, if your motor can breathe a little past 5k rpms, I would go with the 3:73s.

Just looked at your sig, and that's a decent cam, go with 3:73s.