I'll buy your extra tranny and you can use the extra money to buy the torsen diff for your existing tranny. Unless you are going to drag race and have hard-core power with turbo and nitrous, you don't need two trannys. All you need is one built up one and you may as well use the one designed for your car. The work on your stock trans will take all of 1-day and you can be putting it back in on the 3rd day with a nice new clutch, diff, etc.
