speedo correction
 

With my new 3.73 rear end my speedo is at least 20 over. how do I fix it?

MadZ28 tune? A hypertech power programmer came with my car which is how mine is corrected for the gearing.. I would go the route of getting a tune since that is cheaper however :)

my car is older than yours

I am going to assume that you have the gears in the gauge cluster. I don't believe its as easy as it is with the 4th gens..

change the gear in the trans tail shaft, any trans shop should have a bucket full of them

how much should it cost to do this?

not much, last time I got a gear it was $2

sweet