I have changed from 4.10s to 3.54 s and put 265/75s on my 2wd auto. Can the speedo offset be corrected by a dealers odb1 scanner or do I need to replace the send drive gear on the side of the tranny it's been that way for over a year now and I've been useing a scan gauge to want my speed but I really need to get it corrected for the odo.

 

I think the dealer can do it but some have been known to say no because if you are running bigger tires they claim it falls under some emissions BS. But since your's is a great swap it it might be different. I need to have mine done as well. I have been looking at this Superchips tuner for tires....called the Tirepaq or something. I don't know if it will do my 12V though.