wrong rpo gear ratio code?

[briscojones]

I have a 1995 GMC Yukon SLT 2door 4x4,the rear diff came apart on me, the RPO code is GU5 and G80. The GU5 shows to be a 3.23 diff but on the ring gear it has the numbers 1 12 41 11 94 the ring gear has 41 teeth and the pinion has 12 teeth I come up with a 3.42 ratio . can the true ratio be identified with the vin number ? thanks

[Chris]

Does the vin of the RPO tag match the vehicle? Has it maybe been changed in the past? Are you sure you didnt miscount? A 3.23 has a 42 tooth ring and 13 tooth pinion