yesterday, I got under my 88'SC and found the 3 digit code 6HP on the right rear axle. Inside the car was the code GU2. Are the two codes consistent and are the axles 26 splines. Thanks in advance.

 

GU2 is 2.73 gears. I dont know axle codes tho.
About the spline count, 88-90 were changeover years. I have heard many different stories as to when GM switched from 26 to 28 splines. Your best bet is to count yours, as it could be either. But my guess would be 26 spline.

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6HP: STD 2.73:1

GU2: STD 2.73:1

Yep, they match.

I don't think anybody knows for sure what years they started the change, and what year was the last for 26, buy my '87 is 26, and you are better off counting them for yourself then listening what others tell you.

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