how to find gear ratio

[66chargeragain]

I am trying to determine what the gear ratio is on my '66. It is a 383 with 727. Is there a way to tell without taking taking it apart? There is no tag and I doubt if it is original.

[bull]

One way is to decode the VIN if you know it's original.

Another way is to mark the driveline, jack the back wheels up off the floor and count the driveline revolutions per one wheel revolution to get an idea (for Sure Grip). Many people turn the wheel 10 times to get a more accurate average. If the driveshaft rotates about three times the gear ratio is around 3.0, 3 1/2 times, 3.5, 4 times 4.0, etc. I believe you have to rotate the wheel twice as much on an open rear end, but I'm not totally sure.

http://www.youtube.com/watch?v=i_Enyf67KTs&feature=related

[John_Kunkel]

With an open differential raise only one wheel clear of the ground and rotate the tire two full revolutions while counting the driveshaft revolutions...the number of driveshaft turns is the gear ratio.

[c00nhunterjoe]

Its not difficult to remove the pumpkin. The ring is labled. And while its out you can clean 40 years of crud and put fresh fuid in.

[66chargeragain]

With an open differential raise only one wheel clear of the ground and rotate the tire two full revolutions while counting the driveshaft revolutions...the number of driveshaft turns is the gear ratio.

Thanks guys, will check on the week end.