Confirm Gear ratio

OK, I'm thoroughly confused...

As in my other posts I've been trying to get my parts ready for installing my TRD Kauma LSD and supercharger.
All posts I find while researching gears all say that my truck came with 3.9 gears.

Well, I looked at my VIN sticker and the code is A03A.
Which is gears of 4.10

2001 SR5 4.7 4X4

I just put in new fluid but didn't think to confirm the gears, really wish I did...

Can anyone confirm?

 

The spin and count method is the most accurate.

 

I don't think you can really see into the differential when changing fluid...

I'd go by the sticker in the door jamb with the code.

Here's some more info, about half way down the page....
https://old.lcengineering.com/LCTechPages/TECHGEARJANUARY.html

 

I meant I opened the diff when changing fluid.

And the VIN sticker is where i got the code

 

That's likely going to be your best bet outside of what @Casper421 suggested.