1974 Deville Third member

I don't suppose anyone knows what type and size the ring and pinion would. I have a thid member that came out of a 74 deville and I would like to try to find a diffrent gear for more low end.
Thank you for your help.
Tom

Cadillacs are odd. They use a different rear axle design than any other GM division, so only a Cadillac gear set will fit.
The first thing to do is count the teeth and figure out what you have. However, anything much more than 3:1 is exceedingly rare.
Try a lower profile tire, such as a P225/60R15. It will shorten up the gearing a bit and give you better handling to boot.

So basiclly they had a ring and pinion that was all their own and finding an after market gear is next to impossable?
I really didn't think that I would be able to find a radical gear for it. I might see if I can get one costom made. Thanks.