I have a 70 chevelle I want to upgrade the ratio of the box. I saw on the artical about the steering that the 70 chevelle came with a 17:1 - 12.7:1 how would I find out what ratio I have?
Thanks
Tony

http://www.corvettefaq.com/acar/1964-74ChevelleStrgGearBoxes.xls

The alpha code is usually found on an oval sticker on the top of the gear box. Some times it is also stamped on either the top cover or end cap, but most of the older boxes used the stickers.

Standard box was 24:1, power box was variable ratio in 70. 16:1 on center and 12.4:1. 2.9 turns lock to lock. Don't think there were any options.