How to tell what rear or gears is in an OBS truck

[scarbrow]

I was curious to know if you guys know what rear/gears were in which OBS trucks.

I didn't know if there was a general rule of thumb or what.

Anyways I have a 1990 2WD reg cab short bed (stepside) had a 350/700R4 from the factory.

Thanks

[oleshifty]

sticker in bottom of glove box...


the RPO codes is a sticky on here.

Chances are you have a GU4, gu6, or gt4...then a g80 means factory locker

[r6z4o6]

Pop the cover, count and divide! Tried to spin and measure tires, but couldn't get it dead nuts.