speedometer help?

i was driving my car for the first time since last summer today, and i realized that the speedomter is off.....by a lot, at least 10 mph. except i cant understand why, the axle was replaced and the tires were replaced, but stock sized tires were put on, and a stock axle was put on with the stock 3.27 gears.

any ideas of why it is off by so much?

or how to fix it?


any info at all would be helpful

anyone?