I have a 96 grand marquis ls with the digital dash and I would like to swap out the 2.73s for 3.55s how do I reprogram the speedometer?

 

No reprogramming necessary --
Your 2.73:1 to 3.55:1 gear change requires a 21-tooth speedometer gear. That's it.
My question is:
WHY in hell would anyone do such a gear-change on a 2-ton sedan !??
What benefits do you EXPECT from the gear ratio change ?
I mean, even with the gear change, some girl in a Camry V-6 will probably leave you flat in your 2-ton, 4-door sedan.
But hey, give it a go and tell us how it went. ;>

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