1974 Dodge Dart Sport rebuild

Need some thoughts on this build sheet. It shows D AXLE 51 and D8 SIZE 1
I read this as D51 axle and D81 size. Now comes the issue. I show D51 as a 2.76 ratio and D81 as a 7.25" axle. That is not what this car has, It is definitely an 8 1/4" axle with a 2.94 ratio. From the rust/age this axle has not been changed nor have the gears. Am I reading this sheet wrong and it should be the D81 being an 8 1/4" axle and D51 being a 2.94 ratio? Little help please.

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