Rear axle ratio ?

[Tom S.]

What would be the standard axle ratio on a 70 390 h.p. with the turbo 400 transmission? Would the standard axle also be the most common? Thanks in advance! Tom

[Jim T.]

Re: Rear axle ratio ?

According to my 70 owners manual the 70 390 standard rear is 3:08, the optional 2:73 was available for even better gas milage on the highway. All 70's came with posi-traction, first year as standard equipment.

[Tom S.]

Re: Rear axle ratio ?

Thanks Jim for your quick response. I am looking at one but the seller didn't know what rear! He doesn't know if the tank sticker is on it either! He either doesn't know much about vettes or doesn't want to? Tom

[Jim T.]

Re: Rear axle ratio ?

You are welcome Tom. Back when I depended on my 70 as a daily driver I did a good amount of highway/interstate driving, my 70 has the 350/300 turbo 400, I wondered how it would be to have the 2:73 gears that was only available with the 454. With the 3:08 it shifts from second to third above 90 mph.

[James G.]

Re: Rear axle ratio ?

If you look at the bottom of the diff adjacent to the mounting plate on the bottom there will be a group of letters and numbers. The number are the dates and the 3 digit letters like'CAL for 3;08' tells what the ratio is. In 70, you could order 2;73,3;08,3;36,3;55,3;70 rear ratios.