I just bought a 71 with an 83 280zxt engine - wow, I love the car. However, it has the old 4 speed and R180 differential and I would like to put a five speed in it. I have the Borg - Warner T-5 and R200 3.54 out of the 83, though I've heard the ratios and shifting feel of this tranmission are not so good. Would I be better off using a regular 5 speed and a 3.90? If I did use the T-5, would I have to modify the driveshaft?