I just bought a 1995 Chevy C3500HD Chassis cab. I was wondering what rear axle ratio I had. I had the guys here run me a build sheet and I need help decoding the production codes! What is the production code for the 4.63 Ratio? The 5.13 Ratio?
Any help would be greatly appreciated, Thank You!

4.63=gk9 rpo code 5.13=hc7 rpo code