8 3/4 pinion splines

So ,I finely got around to disassemble my 741 housing. The new ring and Pinion has 29 spline pinion, as all the parts catalogs show. But mine has a 10 spline pinion .
I measured the Pinion thickness, both old and new are 1 3/8 thick anyone ever run across this before?20220305_145738.jpg