A little late night investigation on the net and it looks like the heating elements are the following:

manufactured by: ZB Heizkissen, Part # 0008202198 ref# 30120418

A somewhat available, common part for the 124s, and other models. Not sure if it is really the same or not.

Looks like I could re-build the seats with the elements, and just have the wire runners hanging underneath the seats while I sort out the wiring. Now, looking for the correct wiring connectors for the elements.