Copied from Rincewinds post - 09/05/2006
"Hi,
right, the box in the 260 is from a Mustang. It's the Tremec TR 3650 but the only difference is that 5th gear is a unique gear ratio for the car. The original ratio meant that you were doing about 1200 rpm at 70 mph so you had all of the activity and accel that you wanted through the first 4 gears then you'd get to fourth and it the car would go flat as a pancake and that was it, your cruising interstellar 5th gear.
We had 5th taken out of the box and a new ratio added which gives you what you have today. The box is also the same box that goes in the SV with the same ratios IIRC."
Nich.