Rear end gear forum?

[Touchdown67]

I have a 65 c10 with a 12 bolt rear end, what is the best way to determine what gear ratio it has? The rear end is making a little noise. It has a SB400 with a 700r4 transmission with 275/75/15 radial tires. Would it be good to consider 373 gears?

[m455sx]

perfect choice

['65Burb]

What usually came stock?

[m455sx]

I think 373's

[luvbowties]

Originally Posted by Touchdown67

I have a 65 c10 with a 12 bolt rear end, what is the best way to determine what gear ratio it has? The rear end is making a little noise. It has a SB400 with a 700r4 transmission with 275/75/15 radial tires. Would it be good to consider 373 gears?

Here's a good explanation to help determine ratio. Add to it: "just over 3 revs=3.08; 3 1/4 revs =3.23; 3 1/2 revs=3.55; 3 3/4 revs=3.73; a tad over 4 revs=4.11; 4 1/2 revs=4.56; ...etc."

>> http://www.ehow.com/how_12156231_cal...ear-wheel.html <<

I presently have a 3.73:1 gear, 5.7 Vortec about stock w/headers & 4 bbl, 700R4, and 275-70-15(?..or 265-70-15?) in my '66. I'd say it performs about flawlessly. In overdrive, the 70% reduction of the 700R4 gives (3.73X.70) a 2.61 final drive for hwy cruising. Plus, that extra-low 1st gear provides about all the launch you can get away with around town with so much traffic and so many lawmen.

HTH. sam

[Captainfab]

I just don't understand why no one is willing to just remove the rear cover and have a look. More than likely the oil needs changed. It'll only cost a couple quarts of gear oil, a cover gasket and a little time. Then you'll know exactly what you have inside your differential, and it will have gotten an oil change.