I saw a post a while back about a rear end ratio around 2.2:1. I've never seen that low in anything other than a porsche.
Was a 2.2x ratio available in an Olds or Chevelle 10 or 12 bolt rear end?

 

I know the 67 Turnpike Cruiser had the 252 gear standard I am not sure if lower numerically were available.

 

2.41 was lowest numerical gear in '67 for the 3300 - 3800 series

 

The 77-79 metric rear wheel cadillacs came with 2.21? gearing. That's the only time I've come across one.

Some 80's cutlass' came with a 2.14 i've been told, but I never had one.

Mostly 2 series were 2.41 or 2.73 as previously stated.

 

This might be helpful. I did not read it word for word. Gives a general idea.
http://www.hemmings.com/mus/stories/...feature22.html

Pretty sure my old 69 Impala had 2.29 gears.

 

To answer the original question yes, GM in the mid 70's - mid 80's had a 10-bolt that was the 7.5 metric version had 2.29:1
What are you going to do? Run in Bonneville?

 

That'll be me, blasting across the salt flats in a jet powered, monkey navigated....oh nevermind...
Actually, I've got an LS motor in my 72 442 and 2.73 rear. I use it as a hiway cruiser. It's got a muncie, but I'm putting in a T10 that has a 3.42 1st. It's running 2400 at 70mph now. I can get a 70 chevelle 2.56 rear end locally for under $100. The LS motors run great at 2000 rpm, so I might pick that up.
Anyway, I was just curious what lower gears were available. I've never seen anything under 2.4 or 2.5.

 

I had an '80 Trans Am with a 301 and 2.41 rear gear and couldn't spin the rear tires in the snow!! It would do 140 mph all day long though.

 

Would such a rear end help highway mileage significantly?

 

We've had that discussion here.

It should, but there was some disagreement.

- Eric

 

Depends on how "heavy" your foot is But yes it will bring the RPMs down and therefor save on fuel consumption over a steeper gear.

 

About 10% increase running a 4L60 in OD. A little less with a manual trans. No theoretical stuff, real world experience.
It especially true with SFI motors with cams, heads, intakes, etc designed to run at under 2000 rpm on the hiway. They go to batch fire at about 2400 rpm.