On a 1987 BMW 325, the drive shaft situation looks very similar to me than that of the 1985 model, for manual transmission anyway.

The front of the drive shaft connects with three long bolts and nuts to a rubber disk that’s at the tail housing of the transmission.

The rear of the drive shaft connects with four bolts and 17 mm nuts to a flange that’s at the front of the differential.

To remove the bolts, it’s helpful (arguably, necessary) to rotate the drive shaft, so that each nut can be accessed. To have one or both of the wheels up in the air, and the handbrake loose, is a precondition.

But, to loosen or tighten the nut, it helps to have the shaft NOT move.  It can be a time-saver to have an assistant who engages and disengages the handbrake accordingly.