6 of my 9 squares had the RPO stickers in the glovebox and I think one had it one the fender well under the hood.
As far as standard gear ratio on the RPO code sheets, they can be different each year. The 80 C10 Diesel I had just said Standard Ratio. It happened to be 2.73's. Someone else here had that same thing on their RPO sheet but they had 3.08's. I wouldn't be using "Standard" as way to assume your gear ratio.
As far as 4.11, yes if 4.10 is ratio in the front axle, that is fine. That is so small, it's not any different in variance between tire wear. Say your front tires wear faster than your rears for example. Now you don't want mix and match say a 4.11 and 3.73 or 4.11 and 4.56. Just like you wouldn't run 35 in. tires on the rear and 31's in the front.
Exact gear ratio can vary depending on axle model. I think 12 bolt rear's actually a 4.11, while 14 bolts run 4.10s. Some ratio's you won't even be able to use. For example, Dana 60 has a 3.54 ratio, but you won't find a 3.54 or anything close in the GM 10 bolt. 3.42 is what it uses. Ford 9 inch runs a 4.57 ratio, while Chevy 10 and 12 bolt car ratios 4.56's. 14 bolt full floats run a 3.21 and Dana axles run a 3.23. You won't come across it, but you could match 3.21's with 3.23 and not have a problem. As said, Dana 60 will use a 3.54 and Ford truck axles use 3.55. Point being, you'll see stuff like that might not be familiar to you, but it doesn't mean it doesn't exist. It probably does. My 62 Chevy 1/2 ton even had 3.90 ratio dropout 3rd member. I've even been told some axles can have 2 ratio's close together, like a 4.10 and 4.11 depending on the gear manufacturer. I've never come across that option myself. Pretty much as far as mixing and matching, if the first 2 numbers are the same, go for it. Like the 4.1(0) and the 4.1(1), or the 4.5(6) and 4.5(7), 3.2(1) and 3.2(3).
