Well John Deere only made the JD 2940 for three model years, 1980, 1981 and 1982. The JD 2640 was made from 1976 to 1983.
So either your model number is wrong or you have the year wrong.
Also there are several front axle options on several of the JD utility tractors. Some of them use different spindles too. So maybe the part is not made wrong but you have the wrong one for your tractor.
I would make sure of the model and the year of production. Then you can make sure you have the correct part. IF you have the correct part and it is made wrong it is under warranty. JD will replace it. I would not be modifying a new part.