I have an 87 iroc and already have posi, First of all did that ever come stock on an 86-89 iroc?? Also I would like to still maintain the same comfort on the highway as I do now, but at the same time nocking off alot of time on my ets. I am currently running a 350 tpi with headers, cat back k&n filters and a few other things. I have a 700r4 w/overdrive. I have had different opinions on these gears before. Please help, which gear is the best, and are 3:73's ok with overdrive? also are 3:42's really that much worse then 3.73's? Well lets get a disccussion going here, because I need some advice.

 

with tpi i would go with the 3.42's

 

my 88 iroc-z had posi, just run your rpo codes here. my iroc-z had a 9 bolt with 3.27's

https://www.thirdgen.org/cgi-bin/rpo/index

i thought 3.42's and 3.73's are ratio's for a 10 bolts

https://www.thirdgen.org/newdesign/tech/techdb.shtml


i plan on going from 3.23's in my 10 bolt to 3.42's soon, the tpi seems to response well, thats the intell i get from the searches i ran.