Would anybody know what the gear ratio of the rear end on a stock 1977 C-3 350, automatic would be? Thank you.

 

Here are the codes if you can get the ID of the differential

 

OA 3.08:1

OD 3.36:1

LR  3.36:1

OB 3.55:1

OC 3.70:1

 

 

 

The L48 only had the 3.08 rear gear set, while the L82 had the 3.55 rear gears. The L48 also only came with the 350 trans, but the L82 came with the 400 trans. 

If you want to crawl under it(or put it on a lift), you can check the codes stamped on the bottom, and see what it had originally. That doesn't mean that's what it has now, since a lot of rear gears have been changed over the years, so the only real way to know for sure what it has is to open it up and look.