Are my gears right?

[rockthetruckguy]

I have a 1996 Sierra 2500 4X4. Some time ago I had the rear end replaced due to a broken pinion gear. I do not remember if the speedometer was accurate prior to the work and it was a couple of years before I drove the truck again (long story)

 

The crux of my question revolves around the fact that it is 4WD. Because the speedo is way off, I have assumed that the gears in the rear and the gears in the front may not match. Thus I have not put it into 4WD.

 

I would like to know for sure without paying a mechanic a left testicle to take the covers off of the differentials and look for me.

 

What do I need to do to determine what gears are in the differentials? can it be as simple as counting teeth? or perhaps stamped numbers?

 

 

[2018GMC]

 

 

 

[grampadirt]

The gear ratio will also be stamped on the ring gear as seen on mine.Notice the ''41-9'' = 4:56

 

[grampadirt]

Here's a 3:73 (11 41)