Any one ever see these ID # 9 DP C163 2 I have an 85 iroc v8 posi . Acording to my hanes repare manual it does not exist. Also I am going to atemt to change the gears this will be my first time I am very good around all other parts of the car . Any info will help special tools miscellaneous parts ect. I will not order any parts intill I know the exact gear ratio I have when I pull the cover. How low can they be befor the carrier has to be changed. I want to go whith 342 or 373 the gears are much lower then that now.

 

Pull the cover first. It's the only way to know for sure.

The numbers you posted are miscellaneous casting identifiers on the housing, and have nothing to do with the gears at all. C163 is the date it was cast; 16th day of the Cth (3rd, March) month of a year ending in 3 (83 most likely). Not real useful.

That's a great example of why you need to pull the cover before you order parts.