3.55

Selling my great condition 3.55 ford loaded diff. Came out of my car at 25k miles. Diff oil was changed twice in its life. Reason for sale is I replaced it with a performance pack 3.73 Torsen diff. Only downfall is you need to use your diff cover as I had to use my steel cover on the PP due to...

Howdy, I am trying to go from a 27.3 diameter tire to a 28+ diameter tire and go from a rear axle of 3.31 to 3.73. I know mechanically it will be not so bad but I dont know how to re-calibrate my ECU or speedometer. I could buy a tuner but not sure if that would void my warranty by just...