IN future try ordering by part number from mower spec sheet or maybe proper aftermarket conversion number, there is no such thing as a generic spindle.... For instance I have two different John Deere mowers, and each one has a different part number for spindles and different method of attaching blade to spindle... What type of mower (brand & model) are we discussing here....
IF you ordered by correct part number and it does not fit, then they shipped either the wrong item or a mislabeled item...
STENS parts have always worked for me if I order correct ones....