I was talking with my mechanic about what can be done to increase the speed/power of my 91 Z28. He suggested to first try changing the gears in the rear.

So my questions is:
What should I do? Currently I have a stock rear 2.73 (drums); Do I upgrade to 3.73 gears or do I change the entire rear to a posi with the 3.23? gears?

or

Do I look for a 4GEN rear and do that?

 

Increasing "seat of the pants feel" type of power means lower (numerically higher) gear ratios.

The only factory built bolt in stronger rear ends are the austrailian 9-bolt and the Dana 44 from turbo T/As and Firehawks. They are getting harder to come by but they can be had if you look hard enough. If your budget will allow it, you should buy a complete aftermarket rear end such as a strange Dana 60 (my favorite) or a 12-bolt. They are specially made to bolt in to our cars with no mods necessary.

Dropping to 3.73s will feel very different. I don't like to go deeper than 3.90 in these cars but some guys do. If you are not going to do any big power mods to your engine then you can get by quite a while by just changing your gear set out.

 

3.73 will be too much. You'll have one of those cars with a HUGE launch, but it won't be able to complete a pass on the freeway.

For a TPI motor, 3.42 or 3.23 is about as far as you want to go. Only get the 3.42s if the motor has been modified to rev a bit better htan stock - headers & exhaust, better cam, ported base.

Yes you can look for a 4th gen rear. Alot of those came with gears in that range. Be aware though, you'll need to run wheels with the 4th gen offset; otherwise, with your stock wheels, you'll end up with that super-stupid r¡cer skateboard look where you have these little skinny stock wheels stuck way out past the fenders. The ULTIMATE "poseur" stance. You'll have every serious gearhead within a half-mile of you laughing their butt off.

 

Ok so 3.73 is too much and not really worht it. The conversation with my mechanic started when I asked his advice about swaping the engine out for a 350. Budget was not really an issue (then). I was getting a really good deal from my local car club.

So now that budget may be an issue how much would a new rear cost me? (Complete after market swap).

Or should I just go to the 3.42s an call it a day? (and not swap out at all)

Is this really going to give me more power?

 

you have a drum rear non posi in a 91 Z28?? didnt think those were made. that kinda sucks

look for a brake swap while your at it and get 3.42's if yoru automatic trans. If your manual get 3.73's

gears wont make you more power, it just will make the car quicker by letting the motor use its power better and turn the rear tires quicker thus improving acceleration..

gear swaps are noticable... you'll love 3.42's over those 2.73's

 

Yes I have an automatic. I am assuming the gear ratio based on the spec sections on the boards.
https://www.thirdgen.org/1991-chevy-camaro