Does anyone know which driveshaft I need?

[wmealer]

I'm planning sort of an unusual build, and wondering if anyone knows which driveshaft will fit when I eventually swap everything in.

Picking up a complete rear suspension and diff from a 2000 z3m roadster in the next week or so, as well as a 5-speed auto (ZF 5HP-18) from a 99 M3, which I will eventually mate up with an s52 for my '96 M-sport ti.

I want the auto so my wife can drive it when she wants, so please don't flame me. Anyone know if I can piece together a beefy driveshaft with OEM parts, or will I need to modify (shorten) the existing driveshaft from the M3 auto? Will the front half of the M3 shaft mate up with the rear half from the Z3M, and also be the correct length for my ti?

Thanks in advance!