I had the original 3:89 locker installed in the car and I now find at my age, keeping up with traffic spins the engine more than I wish. So I located a date correct 3:50 posi from Jim Cowles at Shelby Parts and Restoration. It still makes engine spin up bit more than I would like, but it is definitely better ratio for me at this point in life. Have the locker with its original markings bagged and tagged. T10M with Sebring gears, again, from Jim years ago.
Had I to do again, I could have my arm twisted to go to 3:25. But its a real rush to run thru the gears and let it stretch its legs. Get nasty looks from Prius drivers though.