I have just installed my t-3650 trans and went away with the POS t-45. My speedometer is way way way off. I ordered the 23 tooth speedo gear from Texas Mustang parts and they told me that this will help but it will still be off some. Does anyone know how much it might be off ?? My rearend gear is a 4.10.
yeah you need the speedcal. Youre going from a t-45 manual with a speedo gear to a tr3650 with a electronic speedo.