I'm sure this has been asked 1000 times but I can't seem to find my exact situation through the search. I have an 87 camaro with a 700R4 with an electronic speedo. The speedometer uses a "vehicle speed buffer" or "speedometer calibrator" box that is under the dash. I want to change the rear end gears but I am unsure what I have to do to correct the speedo. The local Chevy parts counter told me I would have to have a custom speed buffer box burned for 150.00 by a local speed shop. Is this my only solution? What is the easiest and best way to fix this problem?

Maybe These (http://www.terf.com/) People can help....looks like Their speedo adapter is about the same price as having the buffer burned, but maybe They can do something else cheaper....