I have a Marks Adaptors dual program electronic ratio box for when you fit big tires and need to correct your speedometer. It's he MFK1180 and I've never had it fitted just got it with my landcruiser when I bought it, but it had been used before. Unsure on condition but should be fine.
Here's a link to it (tells you what vehicles it works for etc):
http://www.sleeoffroad.com/installation/MFK1180.pdf
What's it worth and does any one want to buy it?
Cheers.