My rear axle broke on me a while ago and so we went to the junkyard and got a new axle for it. Problem is that ever since the axle was replaced, the speedometer and odometer have not been reading properly. The speedometer usually hangs out around 20 mph no matter how fast I'm going (once I pass 20mph actual speed), and for every 3 3/4 miles of actual distance traveled, the odometer registers it as 1 mile.
I called the junkyard I got the part from and they told me that it was off of an 86 wagon.

My only thought is that the gear ratio in the 1986 differential is different than the gear ratio for the 92 diff. and the since the sensor and diff. aren't a proper match, it's not reading properly.

Is there any way to fix this? help, please. Not being able to tell my speed isn't good, and speeding tickets are getting expensive.
Thanks

Matt Stobbs
(somewhere around) 260,000 miles
1992 240 wagon