Re: speedo out of whack
The diff ratio is marked on the diff itself on the side. But you can just use the speedo gear out of the transmission by comparing it to the colours on the website. Remember your actual diff ratio will be higher then the speedo you have, thats why it's showing the incorrect speed.
By the sounds of it, you have a 2.77 Purple-19 speedo gear in there, and have a 3.23 or a 3.45 ratio diff.
What type of car is it you have?
Pull the speedo gear out, and then compare the colour to the ones on the link.