My friend gave me a good posi unit from a third gen and I know nothing about it. The ring gear is on it and I found two numbers on it.
GM1541758
K603177
If you can give me any idea of what I have that would be great.
Thanks everyone!!

 

Take it to the parts counter and they might be able to id the sucker for you

 

Or just call them....they can cross-reference the GM part number over the phone. The K number is just a serial number. All you really need to know is the gear ratio.....you can determine the carrier size and whether it's for a 9- or 10-bolt from that.