Your best bet is to look at the metal tag bolted on the housing, it will be correct it your gears hasn't been modified. To be more sure but it involves some physical work is to jack it up like dmhines said, that is the only way to be absolutely 100% positive.

 

Like I said earlier, if your window sticker says you have those gears, then you have those gears. Simple as that. There is no reason to believe a new vehicle would have been modified. 3.73 gears cost the same to put on your car as 3.31 or 4.10 gears do. Why do you believe that you don't have the 3.73s?

 

I missed the part where he said new car. Yeah there is no reason not to believe your new car window sticker.

 

Look at the differential housing. It will have a sticker with the ratio on it.

Cheers.

 

Just wondering.. I haven't really pushed it yet since theres only 80 miles on it. But it crossed my mind, 3.73 gears are a high gear ratio figured I'd have a harder pull, but again, i haven't really gotten on it yet.

 

Do you have a tune yet? That will probably give you a better pull if that's what you're looking for. Since your car came with those gears it's probably hard for you to compare it though. Go with 4.10s if you're not happy with the 3.73s. 4.10s and an aggressive tune will make it a completely different experience.

 

If all else fails, find another 2010 mustang with the stock gears....race em...if you beat em then you have 3.73's. =D

 

What's your RPM at a given rpm? Off hand I'm thinking I am at 2200 RPM at 70mph.. but i could check exactaly later today. And to double tap.. 3.73 package does not have the strut brace. Just trust the sticker!!!

 

I already cleared that up, geez quit picking on me (kidding), oh and I haven't seen my car for four months now