I have an 01 grand marquis my pumpkin blew out put a new rear end in from a 01 crown Victorian out of a used police car if that matters speedometer is reading fast and tripping the computer HELP PLEAS
The gear ratio of the rear end you installed is different that your original one. Find out what that ratio is (look for a tag on the pumpkin) and get the corresponding gear for the speedometer output on the transmission.
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