At least some of the automatics are nearly identical in lenght to the 80-81 528i 5-speed which means you might not need a driveshaft if you can find a 5-speed. And the driveshaft is adjustable in lenght so close is good enough. The 5-speeds are not that common but much more so and cheaper than they used to be and make for an even nicer car, though the 4-speed alone is an enormous improvement. In the years I had mine, I went from a 2500 automatic to 2500 4-speed to 2800 4-speed to 2800 4-speed with fuel injection and rotary A/C compressor. Mike