third member gear ratio

I have a "03" trd V6 4x4 excab Taco, can anyone tell me how to determine what the gear ratio is in my rear diff or third member ( and why is it called the "third member" and is the T case the "second member" or what) other than counting the teeth on the ring and pinion?
Thanks for your help

 

https://www.tacomaworld.com/threads/oem-gear-ratio-chart.365138/

 

A/TM B03A/ means 4.10?

 

Should be. If you want to make sure you can turn the wheel and count the rotations of the driveshaft (and vice-versa) but I forget what the math was.

 

Wheel spins 4.1 times per driveshaft rotation

 

Or, if your lazy like me, you get the vin, call your favorite Toyota dealership, and ask the parts guy what gear ratio came* in your truck...


* The vin tells you what your truck came with stock....

 

backwards.

it's 4.1 turns of the drive shaft to one rotation of the tire

 

Whoops! Good catch

 

Yup. Called them up this morning to make sure (and to check for recalls) I have 4.30 like I thought.

 

If you ever have a diff that you suspect has been changed the gear codes on the door might not be accurate. Best bet in this case is to count the number of teeth on the ring gear and pinion. Ring Gear #/ Pinion #= Final Ratio