I have a 68 Charger that I'm putting a built 360 in and found two different chunks for the same price they are both posi units one is a 741 with 3.91 gears that has never been run and the other is a 489 with 4.56 gears the car will mainly be street driven and track every once in a while. I'm on a tight budget since my wife lost her job and don't have extra money for gears for the 489 because 3.91 was the gear ratio that I was looking for. The transmission is being beefed up with high performance parts and has a 3000 stall torque converter. I have 17x9.5 rims with 265/40/17 Nitto's 555 just wondering how the 741 will hold up I tend to have a heavy foot.