pinion identification ?

[pagilman]

Hi, Need help with identifying a ring and pinion? The one on the left was thought to be a 4.30 ratio 8 1/4 when I bought it on ebay but it is smaller than the 3.73 8 1/4 on the right!!! The ring gear or pinion has no markings or numbers on either. The ring gear measurers around 7.7/8ths. I wish i could identify it as it could be a good little drag rear for someone on a budget. Can someone identify it? Thanks Walt:hello2:

 

[GoodysGotaCuda]

count the teeth on the ring, and the pinion. divide pinion teeth (drive) by ring teeth (driven)

For instance, for 4.11 gears, Ring will have 37 teeth, pinion will have nine. 37/9=4.1111111111111111

 

[pagilman]

Mike, I know the ratios, but dont know if it is a mopar ford or chevy. I know the ring and pinion on the right is 8 1/4 mopar. thanks walt

 

[GoodysGotaCuda]

The ring and pinions change size when the gear ratio is changed..

How much i'm not certain on between ratios however. there is some variance in the ring/pinion size when ratios start to change. Maybe someone here knows that one for a fact.