pinion identification ?

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: