This is the time you can see how LRP support can do....if you are indeed using the SXX TC that can support the 4.5 motor and you are indeed running 10.25 final drive...it must be the speedo problem.
Your final drive is fine...TA05 has nothing to do about it, but you have to understand that electronics will fries for sometime NO REASON....contact LRP and see what they can do for you....
When buying speedo/electronics....tech and customer support is a major factor.
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